World War I (1914–18) - events

28 July 1914	Austria-Hungary, Serbia	Austria-Hungary declares war on Serbia.
30 July 1914	Russian Empire	Russia orders the general mobilization of its armies in response to the Austro-Hungarian declaration of war on Serbia.
1 August 1914	Germany, Russian Empire	Germany declares war on Russia.
3 August 1914	Germany, France	Germany declares war on France.
4 August 1914	United Kingdom, Germany	Britain declares war on Germany and establishes a naval blockade of the North Sea, the Channel, and the Mediterranean Sea in order to cut supplies to the Central Powers.
4 August 1914	Germany, Belgium, France	Germany declares war on Belgium and invades Belgium and France.
6 August 1914	Austria-Hungary, Russian Empire	Austria-Hungary declares war on Russia.
23 August 1914	Japan, Germany	Japan declares war on Germany.
26–30 August 1914	Germany	German forces defeat the Russian armies at the Battle of Tannenberg in East Prussia, and halt the Russian advance in the region.
5–10 September 1914	France	In the First Battle of the Marne on the Western Front of World War I, the armies led by General Joseph Joffre halt the German advance on Paris, France.
6–15 September 1914	Germany	At the First Battle of the Masurian Lakes in East Prussia, German forces drive back the occupying Russian troops.
15 September–24 November 1914	Europe	The ‘race to the sea’ takes place as Allied and German forces move northwards trying to outflank one other. This establishes the basic line of the Western Front, stretching from the North Sea through Belgium and France to Switzerland.
28 September–31 October 1914	Poland, Russian Empire	German and Austrian forces attack Russian troops south of Warsaw, Poland, in the First Battle of Warsaw, but are driven back.
5 November 1914	France, United Kingdom, Anatolia, Ottoman Empire	France and Britain declare war on the Ottoman Empire.
14 November 1914	Anatolia, Ottoman Empire, United Kingdom	Sultan Mehmet V of the Ottoman Empire proclaims a Jihad (‘Holy War’) against the British Empire.
8 December 1914		In the Battle of the Falkland Islands, a British naval force under Vice Admiral Sir Frederick Sturdee destroys Vice Admiral Maximilian von Spee's German East Asia Squadron.
24 January 1915	Germany, United Kingdom	In the Battle of Dogger Bank in the North Sea, a British force under Admiral Sir David Beatty sinks the German cruiser Blücher.
3 February 1915	Poland, Russian Empire, Germany	The German army uses poison gas at Bolimov, Poland, on the Eastern Front. It is the first time that they have used poison gas on a significant scale.
4 February 1915	United Kingdom, Germany	Germany declares the establishment of a submarine blockade around Britain from 18 February, and declares that any foreign vessel found in the area will be considered a legitimate target.
7–21 February 1915	Russian Empire, Germany, Austria-Hungary	In the Winter Battle of Masuria on the Eastern Front, the German and Austro-Hungarian armies force the Russian troops to retreat.
22 March 1915	Poland, Russian Empire	Russian forces take Przemysl in the Polish area of northeastern Austria-Hungary (a key strategic point in the Carpathian Mountains) after a siege of 194 days.
22 April–25 May 1915	Belgium	At the Second Battle of Ypres, Belgium, a German counteroffensive pushes the Western Front in southwestern Belgium forward by 5 km/3 mi.
24 April 1915	Armenia, Ottoman Empire	The wartime deportation and massacre of Armenians accused of collaborating with the Allies begins in the Ottoman Empire. 1.75 million people are driven across the Mesopotamian desert, over a million of them dying in the process.
26 April 1915	United Kingdom, France, Italy	Britain, France, and Italy make the secret Treaty of London, under which Italy will join the war in return for land and reparations from Germany and Austria-Hungary when the war ends.
2 May–19 September 1915	Austria-Hungary	An Austro-German offensive begins in Galicia (northeastern Austria-Hungary) with the Battle of Gorlice-Tarnów, breaking the Russian lines.
9 May–18 June 1915	France	At the Second Battle of Artois in France, the French armies under General Henri Pétain push forward in northeastern France, but gain little ground in spite of diversionary British attacks.
3 June 1915	Poland, Russian Empire	The Russian southern front collapses when German forces recapture Przemysl, Poland.
23 June–7 July 1915	Italy	The First Battle of the Isonzo takes place when an Italian army under General Luigi Cadorna tries to force bridgeheads on the River Isonzo at Gorizia and Tolmino in Italy, an area held by Austrian forces led by Archduke Eugene.
9 July 1915	German South West Africa	German forces in South West Africa surrender to the South African Louis Botha.
25 September–15 October 1915	France	At the Third Battle of Artois, French forces attack the German line in northeastern France and in Champagne to the southeast, while a British force, using gas for the first time, attacks the line at Loos on 4 November. Only small gains are made.
14 October 1915	Bulgaria	Bulgaria enters the war on the side of the Central Powers.
22 November–4 December 1915	Anatolia, Iraq, Ottoman Empire, United Kingdom	In the Battle of Ctesiphon, Ottoman troops force the British invaders of Mesopotamia back to Kut-al-Imara, Mesopotamia.
18–19 December 1915	Anatolia, Ottoman Empire	In a highly successful evacuation, Allied troops withdraw from Suvla Bay and Anzac Cove on the Gallipoli Peninsula following the failure of the Dardanelles campaign.
8–9 January 1916	Anatolia, Ottoman Empire	Allied forces are withdrawn from Cape Helles on the Gallipoli Peninsula in the Ottoman Empire, completing the evacuation of troops from the Dardanelles.
8–17 January 1916	Austria-Hungary, Montenegro, Europe	Austro-Hungarian forces attack Montenegro, and the Serbian army flees to Corfu.
18 February 1916	Cameroon	The last German garrison in the Cameroons surrenders to the British general Sir Charles Dobell.
21 February–18 December 1916	France	German and Allied troops meet in the Battle of Verdun in France, the German commander Eric von Falkenhayn planning to sap French reserves in a battle of attrition. By the end of the battle each side has lost about 400,000 men.
15 March 1916	Germany	Germany begins a second campaign of unrestricted submarine warfare.
29 April 1916	Iraq, Ottoman Empire, Anatolia, United Kingdom	The Ottoman army recaptures the Mesopotamian city of Kut-al-Imara from the occupying British forces, following a siege dating from 7 December 1915. 10,000 prisoners are taken.
31 May–1 June 1916	Germany, United Kingdom	The British and German surface fleets clash in the Battle of Jutland in the North Sea, their one major conflict of the war. The British fleet under Admiral Sir John Jellicoe loses a greater number of ships, but succeeds in reaffirming its naval dominance. The German fleet will remain in harbour for the rest of the war.
4 June–20 August 1916	Russian Empire, Austria-Hungary	The Russian armies commanded by General Alexei Brusilov mount the Brusilov Offensive, pushing the Austro-Hungarian line south of the Russian Pripet Marshes, but the attack is blunted by German reinforcements.
6 June 1916	Greece	British and French armies blockade Greece, suspecting that King Constantine is in league with the Central Powers, and only relent when the Greek army is stood down on 22 June.
1 July–18 November 1916	France	French and British troops mount the Battle of the Somme in France, a massive offensive which gains 8 km/5 mi of territory. The British Army suffers 60,000 casualties (including 20,000 dead) on the first day, while the whole campaign results in over 620,000 British and French casualties and about 450,000 German casualties.
27 August 1916	Romania, Austria-Hungary	Romania joins the Allies and declares war on Austria-Hungary.
29 August 1916	Germany	Following victories on the Eastern Front, Field Marshal Paul von Hindenburg is appointed German chief of the general staff (with Eric Ludendorff as quartermaster general) in sucession to Eric von Falkenhayn, whose strategy at Verdun, France, is not working.
4 September 1916	German East Africa	Allied troops under the South African general Jan Smuts take Dar es Salaam, the capital of German East Africa (now Tanzania).
9 October 1916	Greece	The former Greek prime minister Eleutherios Venizelos arrives in Thessaloníki (English Salonika), Greece, to establish a provisional government supportive of the Allies.
December 1916	Europe	The ‘turnip winter’ in Central Europe sees food shortages caused by the Allied naval blockade and a high mortality rate among the civilian population.
1 February 1917	Germany	Germany announces its return to a policy of unrestricted submarine warfare in order to cut off the supplies sent to the Allies from the British Empire and the USA.
1 March 1917	USA, Mexico, Germany	The publication in the USA of the ‘Zimmermann telegram’ causes outrage. The telegram is a message from the German foreign minister Arthur Zimmermann to the German ambassador in Mexico City, Mexico, which states that if war breaks out between Germany and the USA, the ambassador is to propose an alliance with Mexico and support Mexico's reacquisition of territory lost to the USA in 1848.
4 March–5 April 1917	Germany, France	German troops withdraw to the specially constructed ‘Hindenburg Line’ on the Western Front. The line is a defensive system in which weak points found in the previous front line have been avoided.
2 April 1917	USA	The US president Woodrow Wilson calls a special session of the US Congress to debate a declaration of war against Germany, telling Congress ‘The world must be made safe for democracy’. The Senate votes 82–6 to declare war on Germany and the House of Representatives votes 373–50 in favour.
16 April–9 May 1917	France	The French commander General Robert Nivelle launches the ‘Chemin des Dames’ offensive (or Second Battle of the Aisne) along the River Aisne. The French forces make tiny advances at heavy cost.
17 April 1917	France	The first in a wave of French army mutinies occurs on the Western Front in protest at the ‘Chemin des Dames’ offensive. A more serious mutiny begins on 29 April, and such mutinies continue until August 1917, ending the French army's capacity to mount offensives.
18 June–13 July 1917	Russian Empire	The Russian minister of war, Alexander Kerensky, launches the Kerensky Offensive on the Eastern Front with a series of attacks against the German armies, which are quickly repulsed with heavy Russian losses.
31 July–6 November 1917	Belgium, United Kingdom	The Third Battle of Ypres (the Battle of Passchendaele) takes place on the Western Front. British forces in Belgium advance about 13 km/8 mi, but at a heavy cost in casualties.
24 October–26 December 1917	Italy	At the Battle of Caporetto, Italy, the Austro-Hungarian and German forces under General Otto von Below break the Italian line and advance 16 km/10 mi. The Italian army regroups along the River Piave.
20 November–7 December 1917	France	The Battle of Cambrai takes place in northeastern France and is the first major battle involving tanks. A British tank force breaks the German line at Cambrai, but their success is not exploited.
3 March 1918	Russia, United Kingdom	A British force lands in Murmansk, Russia, to aid anti-Bolshevik forces and keep Russia in the war against Germany.
21 March–5 April 1918	France, Germany	The German army launches a spring offensive on the Western Front with the Second Battle of the Somme, and advances 64 km/40 mi towards Paris, France.
21 April 1918	Germany	Manfred, Freiherr von Richthofen (the ‘Red Baron’), German aviator and leading ace during World War I, is shot down and killed in Vaux-sur-Somme, France (26). It is not certain whether he was shot down by Canadian pilot Roy Brown or by ground fire.
15–23 June 1918	Italy, Austria-Hungary	In the Battle of the Piave, Italy, Austro-Hungarian troops cross the River Piave to attack the Italian line, but are resisted.
15–18 July 1918	France	At the Second Battle of the Marne, Allied forces halt the German advance towards Paris, France, and begin to advance along the Aisne-Marne front.
3 August 1918	United Kingdom, Russia, Japan	A British force lands at Vladivostok, Russia, beginning a joint effort with France and the USA to prevent Japanese aggrandizement in Siberia.
8–11 August 1918	France, United Kingdom, Germany	The Battle of Amiens is fought on the Western Front, British forces breaking the German line to such an extent that 8 August becomes known as ‘the black day of the German army’.
15–24 September 1918	Serbia	An Allied (French, British, Italian, and Serbian) offensive makes large gains at the Battle of Monastir on the Macedonian front.
18 September 1918	Palestine, Ottoman Empire	A British offensive begins in Palestine when troops under Sir Edmund Allenby defeat an Ottoman force at the Battle of Megiddo.
24 October–4 November 1918	Italy, Austria-Hungary	The Battle of Vittorio Veneto on the Italian front leads to the collapse of the Austro-Hungarian army.
11 November 1921	USA	The Unknown Soldier, whose body has been lying in state in the Capitol rotunda in Washington, DC, is buried at Arlington National Ceremony, Virginia, as a memorial to all other unidentified US soldiers killed in World War I.