Underlying causes

Nationalism and trade barriers

By the early 20th century, the countries of Western Europe had reached a high level of material prosperity. However, competition for trade markets and imperial possessions worldwide had led to a growth of nationalistic sentiment. This nationalism created great political tension between the single-nation states such as France and Germany, and threatened the stability of multi-nation states such as Austria-Hungary. These tensions were reflected in jingoistic propaganda, an arms race between the major powers, and trade barriers and tariffs which exacerbated tensions further.

German militarism and expansionism

In Germany, the close involvement of the military aristocracy in politics and commerce gave these tensions a militaristic slant. Germany's existence as a unified state dated only from 1870, and its late start in the European scramble for world empires prompted some Germans to look to territorial expansion in Europe itself as a means of making up lost ground. This attitude built on a deep-seated German fear of ‘the Russian menace’.

Even the least militaristic of Germans understood the need for access to raw materials, ready-made trade markets, and outlets in colonial possessions for their country's surplus people that the empire had brought to Britain. The small German colonial empire had to be guarded by a powerful navy, but the expansion of the German Navy was regarded as a direct threat in Britain. Similarly, German diplomatic efforts to recover the stability of Bismarck's day in Europe by combining Central Europe into a formidable bloc exacerbated fears of German expansionism in France and Russia.

British fears

In 1902 Lord Lansdowne, British foreign secretary, abandoned the previous British policy of isolation. He concluded the Anglo-Japanese Treaty, relieving Britain of large naval commitments in the Pacific, and the Entente Cordiale with France in 1904.

Outbreak of war

Assassination in Sarajevo

Widespread nationalistic unrest in the Balkan provinces of the Austro-Hungarian Empire had resulted in strained relations between Austria-Hungary and Serbia, regarded as sponsor of the nationalist movements. While visiting Sarajevo, capital of the Austro-Hungarian province of Bosnia-Herzegovina, on 28 June 1914 Archduke Franz Ferdinand, heir of the Austro-Hungarian emperor, was assassinated by a Bosnian student, Gavrilo Prinzip, backed by the Serbian nationalist Black Hand organization.

The Austro-Hungarian government sought to punish Serbia for the crime and Germany promised support, despite the danger of involving Russia, ultimate patron of the Balkan nationalist movements. Austria-Hungary presented Serbia with an ultimatum on 23 July, requesting a reply within 48 hours. Serbia, on Russian advice, agreed to all the demands except two which conflicted with its authority as a sovereign state. Austro-Hungarian armies near the Serbian border were mobilized.

Austrian attack on Belgrade

Russia mobilized its forces against Austria-Hungary on 29 July. On the same day Austrian artillery bombarded the Serbian capital, Belgrade, while the German High Seas Fleet was transferred from the Baltic to the North Sea. News of the Russian mobilization reached Berlin on 31 July; Germany demanded that Russian mobilization should cease, and asked France for a notification by 1 p.m. the following day that it would remain neutral in the event of a Russo-German war, despite treaty obligations to Russia. Long-established German war plans envisaged a crushing blow against France as a precursor to concentration against a Russian invasion.

Belgium

Sir Edward Grey, the British foreign secretary, asked for renewed assurances that Belgian neutrality (guaranteed by the Treaty of London 1839) would be respected. France gave these guarantees, but Germany's answer was evasive and Britain formally notified Germany on 1 August that it could not ignore a threat to Belgian neutrality. On 2 August German troops entered Luxembourg, and shortly after there were skirmishes between French and German troops in Alsace.

Meanwhile, Germany demanded the right of passage through Belgium to counter possible French moves. Asquith, the British prime minister, issued orders for the mobilization of the Royal Navy on 2 August. On 3 August Belgium rejected the German demand and Germany declared war on France; on the same day Britain told Germany that it would stand by the 1839 Treaty guaranteeing Belgian neutrality and would protect the French coast. Germany invaded Belgium on 4 August. Britain demanded German withdrawal. There was no formal reply, and so from midnight on Tuesday 4 August 1914 Britain and Germany were at war.

Western Front, 1914

Initial German operations were conducted according to the carefully prepared Schlieffen Plan, which specified the advance of the most powerful German armies through Belgium, pivoting on the Ardennes, while lighter forces in Alsace and Lorraine fell back if necessary before the French. This would bring the French armies out of their prepared positions, making the heavy blow through Belgium and northern France more dangerous and more difficult to stop.

The German aim was to capture Paris and to trap the advancing French armies in the east between the German defences to their front and the successful German armies in their rear. France would quickly be forced to surrender and Germany could deal in turn with Russia, the real object of its war plans.

Belgian resistance held up the Germans for two days at Liège, but the city was occupied on 7 August and the surrounding forts a week later. German troops then overran half of Belgium, occupying Brussels on 20 August. Belgian forces withdrew northwards to Antwerp. The fortress of Namur, the last barrier between the German advance and the French frontier, was quickly reduced by German siege artillery.

Marshal Joseph Joffre, the French commander-in-chief, ordered offensives into Alsace and Lorraine on 10 August but these made little headway. The small British Expeditionary Force (BEF) under Sir John French reached France to find that there was no effective French plan against a German advance through Belgium. The French 5th Army was driven back from Charleroi on 22 August and the 3rd and 4th armies retreated the same day. French's BEF was left isolated near Mons, and attacked on 24 August by a German force two or three times larger than expected. Driven back with heavy casualties, the BEF began a long retreat through northern France, while Joffre struggled to keep his armies together and to transfer troops to the left flank for a counter-attack. By Friday 28 August the British 2nd Corps had reinforced Sir Douglas Haig's 1st Corps in the BEF.

To the west, German cavalry now swept across Belgium as far as the River Lys and south towards Lille and Arras in an attempt to cut communications between the BEF and its bases at Boulogne and Dieppe. French moved his base south to St Nazaire, leaving the Channel ports open to the Germans. However, the German commander-in-chief, Helmuth von Moltke, remained intent on destroying the French armies northeast of Paris, in the hope of dictating peace on German terms before the autumn.

On 4 September Joffre at last ordered a counteroffensive east of Paris. The attack developed into the first Battle of the Marne 6-10 September. By the end of the week, the Germans had been forced back onto a line running from the River Oise to Verdun. In Lorraine the Germans were also pushed back from Nancy to beyond the River Meurthe. The Allies followed up by attacking the German positions along the Aisne on 13 September, but were unable to dislodge the enemy from the high Chemin des Dames. German attempts to outflank Verdun left them with a large salient at St Mihiel which they held for most of the war.

The lines now began to stabilize between Reims and the Alps as both sides settled into entrenchments. In northern France and Flanders, successive outflanking manoeuvres by both sides, known as the ‘race to the sea’, extended these trench lines towards the North Sea.

The Germans besieged Belgian-held Antwerp on 28 September and took the city on 10 October. The Belgians retreated westward and attempted with Allied support to stem the German advance in the Battle of Yser 15-31 October. Their decision to open the sluices at Dixmude, flooding the country over which the Germans were advancing, proved crucial. Although the Germans captured Dixmude itself, they were unable to cross the river.

Meanwhile the French succeeded in driving the Germans back from Arras, although the town itself was reduced to ruins. The final German attempt to break the Allied line in 1914 came at the first Battle of Ypres, in which Britain's last regular army troops were decimated, but neither side made the decisive breakthrough. With the arrival of French reinforcements on 17 November the Germans gave up their attempts to break through and the line settled down for the winter. On all sides, casualties had been far greater than expected.

Eastern Front, 1914

As German troops were invading France and Belgium, the Russian 1st and 2nd armies, under General Pavel Rennenkampf and Aleksandr Samsonov respectively, launched a powerful offensive against East Prussia on Germany's Eastern Front. By 25 August the light German defensive forces were in retreat, and there was intense alarm in Berlin. Paul von Hindenburg was appointed to overall command in the east, with Eric Ludendorff as his Chief of Staff; they organized a dramatic redeployment and counter-attack in the Battle of Tannenberg (26-30 August), destroying the Russian 2nd Army utterly and driving Rennenkampf back over the frontier. Any advantage Russia had gained by mobilizing more swiftly than expected had been lost - radio messages among the Russian forces were sent uncoded, enabling the Germans to listen in to their plans.

Meanwhile, Austro-Hungarian offensives from Galicia were driven back by four Russian armies in a series of battles involving over a million troops on each side. The offensive against Lublin produced only a temporary Russian withdrawal while in eastern Galicia Russian armies under Nikolai Russky and Aleksei Brusilov overran Austria's eastern borders and threatened Lemberg (modern Lviv, Ukraine; see Lemberg, Battles of). Hindenburg advanced into Russia on a broad front between Wirballen and Augustov in an attempt to relieve the pressure on the Austrians. But Brusilov captured Lemberg on 3 September, and the whole Austrian army group then fell back behind the Vistula and the San rivers. Von Auffenburg, who had defended Lemberg, withdrew to the fortress of Przemyśl, and the whole of the rest of Galicia was in Russian hands by the time of the battle of the Marne in the west. Meanwhile Hindenburg continued his advance until he reached the Niemen; he was checked there and then forced to retreat on 27 September, with the Russians inflicting heavy losses.

Russian cavalry again crossed the German frontier at the beginning of October, and Hindenburg was called south to repel a Russian advance on Cracow. Russian success here would have opened the door to Silesia and to Vienna. Russky was now in command in Poland, and Ivanov, with Brusilov and Dmitriev as his lieutenants, in Galicia. Hindenburg attacked along the radial railway lines leading to Warsaw from Thorn, Kalisch, and Czeştochowa, while the Austrians advanced through Galicia. However, a surprise Russian counter-attack forced back the German left and threatened their centre.

By 3 November the Germans were in retreat, even abandoning Łódź. The Austrians were more successful, recovering Jaroslaw, relieving and resupplying Przemyśl, and threatening Lemberg, but the German retreat in the north compelled the Austrians to retire also. The Russian advance on Cracow was resumed, and by 9 November their cavalry had reached the outskirts of the city.

Hindenburg redeployed his forces and attacked up the Vistula from Thorn on 18 November, threatening the right flank of the Russian advance. Although the Russian centre was broken by General August von Mackensen and the left forced back upon Łódź, the wedge driven into the Russian line was not wide enough and the Germans narrowly escaped encirclement. Reinforcements were rushed to Mackensen, and the Russians withdrew from Łódź on 6 December to prepare for the anticipated German assault on Warsaw. The German advance was held outside the city.

Balkan Front, 1914

Austria's difficulties were not confined to the Russian front. Its ‘punitive expedition’ against Serbia was also disastrously unsuccessful: fierce Serbian counteroffensives under the able Marshal Radomir Putnik defeated the invaders at the battle of the Drina in September 1915, and by 6 December the Austrian armies had been driven from Serbia with over 80,000 casualties, leaving Belgrade once more in Serbian hands.

War at sea, 1914

Allied control of the seas could not guarantee all coasts against German raids, but it did ensure freedom of movement for Allied shipping, and it allowed the Allies to receive supplies from anywhere in the world, while denying the Central Powers access to world markets. The German High Seas Fleet had withdrawn to its bases on the outbreak of war, and the German plan was to wear down the Royal Navy by a war of attrition with submarines and mines. The first serious British naval action was the battle of Heligoland Bight on 28 August, in which three German light cruisers and a destroyer were sunk.

The Germans fared little better in the Far East, where they were forced out of their Chinese naval base at Qingdao by a joint Japanese and British force in September 1914, and Australian and New Zealand troops occupied their colonies in the Pacific. Admiral Maximilian von Spee set out across the Pacific, detaching two of his cruisers, the Königsberg and Emden, to support German forces in East Africa and to raid British commerce in the Indian Ocean. The Königsberg sank HMS Pegasus at Zanzibar on 20 September, but was soon blockaded in the Rufigi River. The Emden bombarded Madras (now Chennai) on 22 September and sank a Russian cruiser in Penang on 18 October. The Emden was eventually sunk off the Cocos Islands by the Australian cruiser HMAS Sydney on 9 November 1914.

Von Spee reached the South American coast and found shelter among the many inlets and islands. He defeated a British squadron off the Chilean coast at Coronel on 1 November, an action that caused severe alarm among the British public. Spee's squadron was overwhelmed by a more powerful British force under Admiral Sir Doveton Sturdee at the Falkland Islands on 8 December. The last ship of his squadron was sunk in March 1915; all German cruisers outside their own harbours had now been destroyed.

War in Africa, 1914

The smallest German colony in Africa, Togoland, surrendered to the Allies on 27 August. The Cameroons repulsed the first Allied attack but by 27 September a joint British and French operation had captured the capital, Duala, and the whole coastline. The conquest of German Southwest Africa (now Namibia) was much more difficult, and was delayed by a serious Boer revolt in South Africa. A joint British-South African campaign in German East Africa met with serious reverses during 1914, and it was to take the Allies four years to secure its final surrender.

1915

Western Front, 1915

While the French began an offensive in the Woevre, the British attacked a small German salient at Neuve Chapelle in March 1915. Both offensives failed to achieve significant success, and revealed the utter inadequacy of pre-war military tactics against trench lines. The failure of a renewed Russian offensive in the Carpathians made it essential to prevent the Germans transferring troops east, and the Allies decided on an attack towards Lille, an important railway centre for supplies to the German line along the Aisne and in Flanders.

Anticipating just such a move, the Germans launched an offensive of their own in Flanders. This developed into the second battle of Ypres, and saw the first use of chlorine gas on the Western front. The German offensive slackened in late May because of Allied attacks near Lens and Lille. Only limited Allied gains were made and the German lines at Vimy Ridge held. New Allied offensive tactics, and new British forces, had again failed to change the hard truth that reinforcements for the defenders could be brought up more quickly than attacking troops could break through a trench line.

By September 1915, the British had around 1 million troops in the field, while the French had some 2 million on a front stretching from Ypres to the Somme. The Allies launched a major offensive from this front, the second battle of Champagne September-October 1915, with the intention of breaking the German lines of communication from east to west. The French made very small net gains while the British took and held Loos, but failed to secure Lens. Attacks and counter-attacks throughout October produced little progress, and the line gradually stabilized for the winter. Sir John French was replaced as commander of the British Expeditionary Force by Sir Douglas Haig in December 1915.

Eastern Front, 1915

During 1915 the main focus of the war shifted from the Western to the Eastern Front. Germany saw that it could more easily defeat Russia than France, as low reserves of munitions could not quickly be built up by limited Russian industrial capacity. The vast salient of Russian Poland was a tempting strategic prize: if the Central Powers could make progress in Galicia, Russian forces in the Carpathians would be isolated and their armies in Poland exposed to a concerted offensive from north and south.

Moreover, the Russian centre in front of Warsaw was weakened in January 1915 after requests from the Western Allies that Russia should divert German troops from the west by attacks on the extreme flanks of the German-Austrian lines in the east. Mackensen took advantage of this dispersal to launch a fierce attack on the Russian centre at Bolimov in February 1915, but it petered out when Russian reinforcements were brought up. After the fall of Przemyśl on 22 March, the Russians were free to make further assaults in the Carpathians, with some initial success, but German reinforcements and the Russian weakness in guns and material left the strategic passes into Hungary in German-Austrian hands.

Mackensen began a fresh offensive on 2 May with an overwhelming artillery bombardment. The Russian defences were completely destroyed and the Germans crossed the Biala, taking Gorlice and breaking Dmitriev's line. This advance compelled Brusilov to retire hastily from the edge of the Carpathians with heavy losses and by 18 May Mackensen had seized the line of the San from Sieniawa to Jarosłav. By 20 June he had cut Russian communications north of Lemberg, and the capital of Galicia once more fell into Austrian possession on 22 June. The German advance achieved all its objects except the complete defeat of the remnant of the Russian armies in Galicia, and they now swung round to face north, towards Poland.

The Germans planned to encircle the Russian position in Poland by striking at Vilna from the north while Mackensen's Galician armies moved against the railway between Lublin and Kovel. German forces under General Max von Gallwitz advanced from the north in mid-July, taking Lublin and Cholm by the end of the month. Faced with this converging offensive, the Russians decided to abandon Poland and evacuated Warsaw on 5 August. Their fighting retreat left the whole line from Brest-Litovsk to Kovno in German hands. The Germans made further advances until Russky was restored to command of Russia's northern armies and succeeded in stabilizing the line.

Balkan Front, 1915: the Dardanelles campaign

The Turkish entry into the war on the side of the Central Powers at the end of 1914 had cut Allied supply routes to Russia and increased the isolation of Serbia. The arguments for a direct blow at Turkey via the Dardanelles were strong. An Allied offensive here would forestall Turkish attacks on British Egypt. Romania would be encouraged to join the war on the Allied side, and an Allied victory would deter Bulgaria from following its inclination to join the Central Powers. Italy's position as a member of the Triple Alliance who had not yet taken up arms was also an important consideration.

The campaign began with a naval attack on 19 February 1915, which served only to alert the Turks that a major offensive was likely. Three squadrons of British and French ships were sent up the straits, only to meet Turkish floating mines and artillery batteries which took a heavy toll: one French and two British battleships were lost.

The main attack began on 25 April with landings at Gaba Tepe (Anzac Cove) and Cape Helles, but the advantage of surprise had been lost. The landings were poorly executed, confused, and costly, and little progress was made from the beachheads. The struggle for Gallipoli settled into a hard-fought campaign against almost impregnable Turkish positions. In a second attack 6-8 May naval bombardment failed to destroy Turkish defences, and the Allies managed to advance only a few hundred metres at a heavy cost; by the end of May the Allies had lost more troops at Gallipoli than the total British losses in battle during the entire South African War. A third attack on 4 June confirmed the impression that nothing short of a large army could master the position against brave and determined Turkish defence.

Heavy Turkish attacks were held throughout June and July, when Allied reinforcements arrived. A fresh assault began on 6 August when Allied forces at Cape Helles launched a general attack on Achi Baba as a diversion from the main offensive against Chunuk Bair and Suvla Bay. There was fierce fighting throughout the month, and heavy casualties; although the initial beachhead was enlarged, the Allies failed to make a significant breach in Turkish lines.

By November it was obvious the campaign had been an expensive failure and the Allies began to evacuate the peninsula; the final embarkations from Suvla and Anzac took place 18-19 December, and of Cape Helles on 9 January 1916.

Allied expedition to Salonika

Both sides spent much of 1915 engaged in secret diplomacy to persuade Bulgaria to join the war, and the Bulgarians had demanded territorial concessions as the price of their assistance. As the Allies could satisfy Bulgarian demands only at the expense of Serbia, their ally, or Romania and Greece, potential allies, their promises were half-hearted. Germany, on the other hand, offered Serbian Macedonia, Salonika, and Epirus - an offer formalized in a treaty signed on 6 September 1915. A joint Austrian-German attack was launched against Serbia on 19 September. Greece demanded that France and Britain send 150,000 troops to Salonika. Bulgaria mobilized its army on 22 September, and the following day King Constantine of Greece gave the order to mobilize the Greek army. Bulgaria began to mass forces on the Serbian border on 24 September, finally invading Serbia on 11 October, two days after the Germans had captured Belgrade. The Allies' forces at Salonika were unable to turn the Bulgarian flank and failed to prevent Serbia being overrun. The Allied forces fell back and retired into Greece in mid-December. The decision nevertheless to maintain an Allied presence at Salonika throughout the war tied down large numbers of soldiers who could have been better employed elsewhere.

Italy

During the winter and spring of 1915 prolonged diplomatic efforts had been made to bring Italy into the war. Despite treaty obligations to Germany and Austria-Hungary, Italy remained neutral while negotiating with both sides for territorial concessions. In the end the Allied offer of Austrian and Turkish territories proved conclusive, and in June the first offensive by the enthusiastic but inexperienced Italian army was launched against Austrian positions along the Isonzo. Casualties were huge, and five further offensives by December brought little gain.

Middle East, 1915

A British force from India had captured Basra in November 1914, and Turkish operations in December 1914 had failed to dislodge it. As Turkish attacks continued during April and May the British decided to advance north. By July what had started out as a limited advance had become a general push on Baghdad. Maj-Gen Sir Charles Townshend took Kūt-al-Imāra on 29 September, and by 22 November British forces had reached Ctesiphon, where a fierce battle raged for two days until they were forced to retreat. The surviving troops reached Kūt on 5 December 1915, and a five-month siege began. Four Turkish divisions surrounded the town and relief forces were unable to break through. Townshend was forced to surrender on 29 April 1916.

1916

Western Front, 1916

At the start of 1916 the new German commander-in-chief, Erich von Falkenhayn, decided on an offensive against the French fortress at Verdun. His main object was a campaign of attrition to wear down the French army, still the mainstay of the war effort of the Western Allies. The Germans were to employ a new tactic: powerful but limited attacks would seize the French front line, then immediately dig in while artillery support was brought up. The inevitable French counter-attacks could then be decimated by well-supported and dug-in defenders, after which the process could begin again. A short, intense bombardment began on 21 February; by far the fiercest bombardment yet experienced, it obliterated the first French lines, broke up the communications trenches, and even altered the shape of the hills. By 25 February the Germans had broken the French front at Douaumont, but were halted by the defensive tactics of General Henri Pétain, one of the first French commanders formally to abandon the policy of swift counter-attacks. The second phase of the battle began with an attack from the northwest on 6 March, as German efforts shifted to the flanks of the salient; the French fell back but again stabilized their line. Despite renewed efforts on the part of the Germans, they made little progress towards Douaumont. German attacks on the lines between Avocourt and Béthincourt were successfully counter-attacked by Pétain and fierce fighting continued until mid-April. By then it was clear that the German offensive had failed: the most brutal and horrific fighting of the war to date had cost the Germans almost as many casualties as their opponents - and Verdun was still in French hands. Although further attacks and counter-attacks continued, the German effort was hampered by the need to move troops to the Somme, and the battle had died away by December 1916.

The next major offensive on the Western Front was the Battle of the Somme 1 July-18 November 1916. This was the offensive for which the British ‘New Armies’ had been preparing since 1915, the ‘Big Push’ which would finally break the trench deadlock.

A week-long bombardment of the German lines failed to destroy their defences, and the partly trained British troops were cut down as they emerged from their trenches: over 19,240 were killed on the first day. In over four months of some of the bloodiest fighting of the war, the Allies gained barely 8 km/5 mi at a cost of over a million casualties. The carnage on the Allied side of the Somme offensive was, however, matched by similar suffering on the German side. The battle is also notable as the first in which tanks were used.

Towards the end of the Somme offensive, on 24 October, the French launched a surprise attack on German positions at Verdun. From Fleury to Fort Douaumont positions which had taken the Germans months to win were recovered in a few hours. Further gains were made during November and by mid-December the Germans had been driven back almost to the positions from which they had started.

Eastern Front, 1916

By June it appeared that Italy might be overwhelmed if the Austrian Trentino offensive succeeded, and in order to relieve this pressure Russia launched the well-supplied and brilliantly planned Brusilov offensive on 4 June. By the end of June the Austrians were in full flight towards the Carpathians. The Russians continued to make advances throughout July and August until the offensive was finally halted by lack of supplies and the failure of other sectors of the Russian front to support the push. Although a huge success in terms of its immediate objectives, the offensive was partly responsible for Romania's disastrous entry into the war and the enormous cost in casualties contributed greatly to the disillusionment of the Russian people with the war, leading to the Russian Revolution of 1917. The rapid series of Russian successes also led to a complete overhaul of the Central Powers' command structure: most of the Austrian commanders were replaced by Germans and Austria's role in the coalition was significantly diminished for the rest of the war.

Romania enters the war

Encouraged by the Russian advance in Bukovina in June 1916 and Allied offensives in the west, Romania declared war on Austria on 27 August. Germany in turn declared war on Romania on 28 August followed on 1 September by Bulgaria. Romania's opportunist move was aimed solely at gaining Transylvania which it immediately invaded. The invasion went well initially: within a fortnight most of the frontier towns had been occupied. The Central Powers dispatched Falkenhayn at the head of the new Austrian 9th Army against the Romanian left and Mackensen to the south of the Danube, with both armies converging on Bucharest. Mackensen advanced into the Dobrudja, taking Turtukai on 6 September. Shortly afterwards Bulgarian troops occupied Silistria, and by mid-October the Romanian army was in full retreat. Although the retreating Romanians offered strong resistance to Falkenhayn in Transylvania, by 20 October Mackensen had broken the Russo-Romanian line. Constanţa was abandoned and the Russians hastily withdrew to Babatag.

By 21 November the Germans had isolated the Romanian salient to the west and by 27 November Mackensen had joined up with Falkenhayn. The Germans advanced on Bucharest, which fell on 6 December, leaving only Moldavia in Romanian hands.

Italian Front, 1916

Trentino, then part of the Austrian Tyrol, was Italy's first objective after joining the war in 1915 and fighting in the area had been heavy. The Austrians had strengthened the Trentino front throughout the winter of 1915-16 and launched a massive offensive on 15 May, supported by over 2,000 guns. By the start of June, the Italians had been driven back and the Austrians had come within 30 km/20 mi of Vicenza. The Italian commander, Count Luigi Cadorna, launched a counteroffensive in June and quickly regained ground along the whole front. Despite fierce Austrian resistance, Cadorna continued his advance and entered Gorizia on 9 August.

The Italian offensive now entered its second stage, aimed at capturing Trieste. The advance began on 10 August and within two days the whole of the western end of the Carso was in Italian hands. Cadorna continued to press forward into the Carso, and took Tivoli, northeast of Gorizia. Italy then declared war on Germany on 28 August 1916. The Italians made further advances in the Carso in mid-September and a further attack on 10 October straightened out the front, with 5,000 prisoners taken. Italian progress continued throughout October until they came up against the formidable defensive system of Hermada, covering the road to Trieste. A huge concentration of guns would be needed to take the position and the onset of winter compelled Cadorna to postpone further advance until the spring.

Balkan Front, 1916

The front at Salonika was now held by the British on the right, the French in the centre, and the reconstituted Serbian army on the left. An Allied offensive to take Monastir began August, under General Maurice Sarrail. The French began to bombard Doiran on 10 August and the following day occupied positions on the outskirts of the town.

The following week a Bulgarian counteroffensive penetrated a long way within the Greek frontiers and threatened to turn Sarrail's flank by an advance to the Gulf of Salonika. Sarrail renewed his attack in early September and by 19 November the Bulgarians were forced to evacuate Monastir. Sarrail's campaign succeeded in securing Greece, but failed to relieve the Central Powers' pressure on Romania.

Middle East, 1916

At the start of 1916, Russian forces in the Caucasus were ready to launch the offensive against Turkish positions at Erzurum which they had been preparing for some time. In five weeks of heavy fighting the Turks lost over five divisions. Erzurum was captured in February, and Trebizond in March, the Turkish garrison retreating south towards Baiburt. Russian cavalry occupied Erzingan in July and although further advances were temporarily delayed by Turkish counter-attacks, by 25 August the Russian commander General Nikolai Yudenitch had again resumed his slow progress towards Anatolia.

Turkish plans in the Middle East were shattered by the Arab revolt in the Hejaz in June 1916. The Sherif of Mecca, Hussein ibn Ali, proclaimed Arab independence on 9 June. The Arab rebels, encouraged by the British guerrilla leader T E Lawrence, occupied Mecca and the port of Jeddah, laid siege to Medina, and later cut parts of the Hejaz railway to prevent the Turks sending reinforcements from the north. The revolt spread rapidly and delayed the Turks' projected attack on Egypt. The Turks failed to quash the revolt, and Lawrence's Arab guerrillas disrupted their supply lines for the rest of the war.

The Turks eventually launched their assault on Egypt in August 1916. 18,000 troops advanced on the Suez Canal from the east, where they clashed with British forces at Romani on 3 August. British reinforcements arriving in the afternoon routed the Turks. The British pursued the fleeing Turkish forces, defeating them again on 9 August. Egypt was secured from further attack.

Irish Rebellion, 1916

On the outbreak of war, the Unionist and home-rule leaders in Ireland had declared a truce for the duration of the conflict, but this was far from universally accepted. The Easter rising of April 1916 posed a serious threat to the Britain, but the interception of a German submarine carrying arms intended for the rising and the capture of Sir Roger Casement severely weakened the rising's chance of success. It was crushed after five days of fighting in Dublin. Casement and 15 of the rising's leaders were executed.

War at sea, 1916

The major sea action of the year was the Battle of Jutland on 31 May, in which the British Grand Fleet clashed with the German High Sea Fleet. Although the battle was in itself indecisive, both sides claimed victory: the Germans because they sank more ships than they lost, and the British because the German fleet remained in harbour for the rest of the war. In the long term the latter effect had far more impact on the war as a whole.

German peace note

By the end of 1916 the combined effect of casualties at the Somme and Verdun, the decline of Austrian military strength, and the Allied economic blockade prompted limited moves towards a peace settlement in Germany. The German chancellor announced in the Reichstag on 12 December 1916 that he had sent peace notes to the various belligerent powers, saying that Germany was willing to consider peace as it was now victorious in a war forced on it by its enemies. The note failed to specify terms which Germany would be willing to accept. On 30 December the French government gave the US ambassador in Paris a formal answer, signed by Russia, France, Great Britain, Japan, Italy, Serbia, Belgium, Montenegro, Portugal, and Romania, in which they declared that there could be no peace until Germany offered reparation, restitution, and guarantees for the future.

1917

Western Front, 1917

In the first three months of 1917 the Germans conducted a highly skilled withdrawal to new defences in the so-called Hindenburg Line, prompted in part by the weakening of their Somme positions. The Allies launched a major offensive against the new line in April. The British attack at Vimy Ridge on 9 April developed into the third battle of Arras. The French commander General Robert Nivelle launched another attack on the Chemin des Dames, the disastrous second battle of the Aisne 16 April-20 May which failed to deal the decisive blow Nivelle had planned and cost both sides heavy casualties. Serious mutinies broke out in the French army as a result, and Nivelle was replaced by Pétain.

The focus of attention on the Western Front switched to Flanders where the British launched a major offensive against Messines 7-15 June, quickly overwhelming the German lines with heavy artillery and extensive mining. The next offensive, the third battle of Ypres July-November, failed to build on the success of Messines. Both sides sustained heavy casualties in the Flanders mud, with little Allied gain. The British made initial gains in a subsequent advance at Cambrai 20-23 November but were driven back by a German counter-attack.

Eastern Front, 1917

The Russian effort largely collapsed in early 1917 as the country slid towards revolution and civil war (see Russian Revolution). Although the provisional government installed after the February revolution attempted to continue the war, widespread desertions and Bolshevik agitation negated any serious military effort and shortly after the Bolsheviks came to power in November 1917, hostilities on the Eastern Front ceased. The new regime began discussing peace terms with Germany in December 1917 which resulted in the Treaty of Brest-Litovsk on 3 March 1918. The Central Powers also secured a treaty with Romania on 5 March and newly independent Finland on 7 March.

Italian Front, 1917

An Italian attempt to bypass Austrian defences near the Bosco di Ternova and resume their advance east had failed by May 1917. Cadorna appealed to Britain and France for help in July but although Britain sent some artillery neither could spare infantry and the Italians resumed the attack alone in August 1917. They were driven back by Austrian divisions recalled from Russia and by the end of September Cadorna's main operations were at an end.

Ludendorff transferred Karl von Below from the Western Front to the Italian Isonzo Front in August 1917 and gave him command of six German and seven Austrian divisions. Von Below planned to dispense with the usual preliminary artillery bombardment, and to rely instead on picked storm troops to break through the enemy lines, leaving any strongpoints to be dealt with by follow-up troops. The new method was to be tried near Caporetto, where the Italian troops were reported to be disaffected. The Battle of Caporetto began on 24 October in heavy rain and snow; the disaffected Italian troops broke almost immediately, and the Germans quickly crossed the Isonzo and then the Italian frontier and advanced to the Piave River, nullifying in a day all the Italian gains of the preceding two and a half years.

Balkan Front, 1917

Much of the action on this front during 1917 centred around neutral Greece whose king, Constantine I, was pro-German but determined to stay out of the war. Bulgaria had seized Greek territory in August 1916, sparking a revolt on 30 August at Salonika under Col Zimbrakakis. Regiments were enrolled for service against Bulgaria, and a Greek regiment was sent to the front at the start of September. The Greek opposition leader Eleutherios Venizelos left Athens for Salonika, where he formed a provisional government which immediately declared war on Bulgaria. The Venizelos government gradually gained recognition among the Allies, though the mainland southwest of Salonika remained under Constantine's pro-German rule.

A further crisis occurred when Italy proclaimed Albania independent under its protection on 3 June 1917 and occupied Janina five days later, cutting communications between Greece and the Central Powers. French troops seized the isthmus of Corinth in June, and the Allied high commissioner demanded the abdication of King Constantine. Constantine abdicated in favour of his second son, Prince Alexander, and left for Switzerland on 12 June. Venizelos was formally installed as prime minister on 25 June and Greece officially entered the war on the side of the Allies.

Middle East, 1917

The Allies realized towards the end of 1916 that they must crush the Turks if they were to make any progress in the Balkans, and so reinforced their campaigns in Palestine and Mesopotamia. The British entered El Arish in December and captured Rafa, the last Turkish stronghold in the Sinai, on 9 January 1917. In Mesopotamia British forces again advanced on Baghdad from December 1916, clearing the Turks from the right bank of the Tigris. They entered Kūt on 24 February 1917 without opposition and Baghdad on 11 March. By the end of April Baghdad was secure from enemy attack.

Turkish troops in the Sinai were demoralized, their supplies short and desertion was common. The British launched an offensive to prevent them falling back to stronger positions in Palestine, and advanced up the coast towards Gaza. The Battle of Gaza 26 March-17 April failed to capture the city and the British sustained substantial losses. This was a serious reverse and was followed by a long period of inaction. In October the new British commander, General Sir Edmund Allenby, organized an offensive against Beersheba, intending to outflank Turkish defences and advance on Jerusalem. He created a diversion by shelling Gaza, then launched a successful assault on Beersheba, occupying the town on 31 October. By 7 November Gaza had fallen and Jerusalem was taken on 9 December.

USA enters the war, April 1917

At the outbreak of the war there had been much sympathy for Germany in the USA, compounded by the British maritime policy which interfered with US shipping. In the early months of 1915 Germany introduced new guidelines for U-boat (submarine) attacks and warned the USA that neutral ships might be sunk. The full implication of this was brought home to the US public by the sinking of the liner Lusitania on 7 May 1915 with the loss of 1,200 lives, including US citizens; the outcry was such that Germany suspended its U-boat campaign. The following year, however, German submarines torpedoed the Sussex, a French passenger steamer, injuring two US passengers on board. The USA threatened to sever diplomatic relations with Germany, who responded with the Sussex Pledge, promising not to sink merchant ships without adequate warning and an attempt to save lives first. Relations were also strained by revelations about the activities of German agents in the USA. The Republicans stirred up public sentiment against President Woodrow Wilson's policy of strict neutrality throughout 1916 but he still secured re-election in November. Wilson tried unsuccessfully to mediate between the two sides in December 1916.

On 31 January 1917 the German government announced that all sea traffic within sea areas adjoining Britain, France, and Italy, and in the eastern Mediterranean, would ‘without further notice be prevented by all weapons’, a return to unrestricted submarine warfare. This was finally too much even for Wilson and diplomatic relations with Germany were severed on 3 February. The publication of the Zimmermann Telegram on 1 March caused widespread outrage and when German submarines sank six US vessels shortly after there was no chance of the USA remaining neutral. Wilson was compelled to formally declare war on 6 April. The entry of the USA into the war was of immediate economic and industrial value to the Allies, although no considerable contingent of US troops could be sent to Europe for many months.

The first contingent of US troops landed in France towards the end of June 1917, although it was not until May 1918 that US troops arrived in any numbers under Maj-Gen John Pershing. Meanwhile, the US navy embarked on a massive programme of expansion and sent vessels to aid in the protection of Atlantic shipping. A system of escorted convoys was introduced in May 1917 and losses due to German submarines immediately declined.

The end of the war

Western Front, 1918

In February Ludendorff and Hindenburg proposed a massive push on the Western Front to isolate British forces between the Somme and the Channel so that a heavy German blow could be directed at Paris. Although such a strategy could be costly, the Germans were no longer bound by commitments on the Eastern Front, while France was at the limit of its resources and Britain was severely overstretched by commitments in the Middle East and Italy. If the strategy could be implemented quickly, the war could be ended before US troops arrived in strength.

The German Spring Offensive was launched on 21 March 1918 with a huge assault on the British 5th Army, the second Battle of the Somme, which forced the British back to a line near Arras late April. Although this initial assault did not completely break the Allied line it had achieved more than any Allied offensive of the whole war. By 4 April the Germans had claimed 90,000 prisoners and 1,300 guns, and the Sir Hubert Gough's 5th Army had been partly destroyed. A second German attack at Armentières on 9 April, the Battle of the Lys, recaptured the Messines ridge and drove a deep wedge into the British front, but still did not achieve the breakthrough Ludendorff needed. A third attack launched on 27 May reached the Marne near Château-Thierry and was extended to within 72 km/45 mi of Paris - in the space of a few days the French had lost all the gains they had made since 1914. By now, however, delays in implementing the German plan meant the balance of power was shifting against Germany.

From the start of June the Allies began pushing the Germans back. The Germans were delayed from pressing home their attack until 15 July; Ludendorff's attack on Reims was held and driven back in the Second Battle of the Marne and Marshal Ferdinand Foch's counter-attack with a joint French-US force drove the Germans back beyond Château-Thierry and flattened out the German salient.

The British 4th Army launched a successful offensive at Amiens 8-12 August and the Allied advance continued steadily all along the line. A US assault on the St Mihiel salient, held by the Germans since 1914, was launched at dawn 12 September and finally removed the German threat to Verdun. Both Austria and Germany made overtures for peace with the USA in mid-September, but Wilson's reply was not encouraging. While the British pushed forward in Flanders, with the final offensives around Ypres starting on 26 September, French and US troops were pursuing the Germans on the Meuse-Argonne line. Progress all along the French and British fronts continued throughout October, and subsidiary offensives around Cambrai and Le Cateau pushed the Germans back beyond their Hindenburg defences.

Belgian and French troops under Degoutte and the British 2nd Army under Plumer attacked the whole Flanders front in late October, and by 21 October the Germans had been driven back to the Lys in front of Ghent. German withdrawal was equally complete in the south: Lille and Douai were taken on 17 October, and by 21 October the British had advanced to the Schelde. Ludendorff resigned five days later.

Germany's allies had collapsed by early November, and it was left alone to meet the decisive final battles of the war. The German line on the Meuse was broken on 1 November, and during the next few days the Americans followed up their advantage, reaching Sedan on 7 November. The German centre was broken in the Battle of the Sambre from 1 November; by 9 November Maubeuge had fallen, Tournai was occupied the same day, and early on 11 November the Canadians captured Mons. At 11 a.m. that day fighting ceased all along the Western Front as the armistice came into effect.

Italian Front, 1918

The Austrians launched a final offensive against the Italians on the Piave on 15 June but an Italian counter-attack on 2 July turned the Austrian flank and forced a general retreat. The Austrians escaped with slight losses, and flooding on the Piave prevented the new Italian commander, General Armando General Diaz, from following up his success.

By late October Austria-Hungary itself was close to collapse, but the Austrian army in Italy was still in being. Supported by contingents from most of the other Allied powers, Diaz launched his final offensive on the Piave (known to the Italians as the battle of Vittorio Veneto) 23-24 October. Within a few days, the Austrians were in full retreat and by the end of October Diaz had broken the Austrian front. The retreat became a rout ending only when Austria-Hungary signed a separate armistice with the Allies on 3 November (effective 4 November) and all hostilities ceased, heralding the final collapse of the Austro-Hungarian Empire.

Czechoslovakia had already proclaimed its independence on 28 October; now other Slav states followed suit, and Austria itself became a republic on 13 November.

Balkan Front, 1918

The Allied front in the Balkans had been quiet since the offensive of May 1917, and the new Greek army had largely replaced the French and British. Meanwhile, Bulgarian morale was failing as their government sought a way out of the war. An Allied offensive around Vardar broke the Bulgarian lines and an armistice was signed at Salonika on 29 September. The Serbians entered Nish on 12 October and by 1 November they were in Belgrade.

Middle East, 1918

Much of Turkey's energy in 1918 was taken up with campaigns against the new Bolshevik republics in the Caucasus, in violation of the Treaty of Brest-Litovsk, which led to German fears that Turkish aggression might bring Russia back into the war. Eventually the Turks were beaten back by British intervention and fierce resistance from both Bolshevik and White Russian forces in the area.

Following their capture of Jerusalem in December 1917, Allenby's forces took Jericho on 21 February 1918 and continued to advance through Palestine and Syria. Damascus fell on 1 October, Beirut on 6 October, and Aleppo fell on 26 October. Meanwhile, General Sir William Marshall's forces advanced up the Tigris and forced the Turkish army in Mosul to surrender. An armistice was signed on 30 October and the Allies occupied Constantinople on 1 November.

Russia, 1918-19

After the Treaty of Brest-Litovsk in March 1918, German relations with the Bolsheviks ranged from equivocal association to open hostility. During April and May Trotsky made abortive efforts to raise a Red Army to drive the Germans from Russia, but it was only the intervention of a Czechoslovak contingent in the southeast that forced Germany to make an agreement with Lenin. The Germans undertook not to advance further east than a specified line from the Gulf of Finland to the Black Sea, and the Bolshevik forces were therefore able to give their undivided attention to the Czechs on the Volga. The Ukraine was occupied as a German province but widespread revolt culminated in the assassination in October of Field Marshal von Eichhorn in Kiev. Lenin signed three further treaties with Germany in September although these were negated in the peace treaties which followed the end of the war.

From early 1918 Allied relations with the Bolsheviks had been strained but friendly and the international expedition to Arkhangelsk (Archangel) in March 1918 was initially approved by Trotsky. However, in June 1918 the Bolsheviks demanded the withdrawal of all Allied forces from Russian soil. The Allies began a half-hearted attempt to aid the White Russian forces against the Bolsheviks but by mid-1919 the Bolsheviks were obviously in too strong a position so the Allied forces were withdrawn.

Peace

Towards the end of September 1918 it was obvious that the German offensive in the west had failed, while Bulgaria and Turkey were on the verge of defeat and Austria sought peace at any price. The British maritime blockade had brought starvation to much of Central Europe. A new German government was installed under a new chancellor, Prince Maximilian of Baden, to negotiate with the Allies. Maximilian sent a note to US president Wilson on 4 October, asking for an armistice and declaring Germany's acceptance of his Fourteen Points as a basis for peace discussions. Wilson emphasized that any armistice would have to safeguard Allied military supremacy, implying total surrender, and negotiations began at the end of October. An armistice was signed between Germany and the Allies at 5 a.m. on 11 November 1918, and fighting ceased on the Western Front at 11 a.m. the same day.

The terms of peace were negotiated separately with each of the Central Powers in the course of the next few years:

Treaty of Versailles between the Allies and Germany, signed on 28 June 1919, ratified in Paris on 19 January 1920;

Treaty of St Germain-en-Laye between the Allies and Austria, signed on 10 September 1919, ratified in Paris on 16 July 1920;

Treaty of Trianon between the Allies and Hungary, signed on 4 June 1920;

Treaty of Sèvres, between the Allies and Turkey, signed on 10 August 1920, not ratified and superseded by the

Treaty of Lausanne between the Allies and Turkey, signed on 24 July 1923, and ratified in the same year.

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