Many different battles were fought in the First World War and a case can be made for the importance of them all. This list includes some of the most important ones, which had an impact on the whole shape of the war.
1914
28 June: Austro-Hungarian Archduke Franz Ferdinand is shot in Sarajevo, the capital of Bosnia-Herzegovina
23 July: Austria-Hungary issues an ultimatum to Serbia
29 July: Austria-Hungary invades Serbia
1 August: Germany declares war on Russia
4 August: Germany invades Belgium; Britain declares war on Germany
August: The Russians are heavily defeated by the Germans at Tannenberg; the British retreat from Belgium after holding up the German advance at the Battle of Mons
September: The Germans are turned back from Paris after the Battle of the Marne; the Russians besiege the Austro-Hungarians at Przemysl
October: The Race to the Sea – the Germans and the British and French try to outflank each other but end up with an unbroken line of trenches along the whole Western Front
November: The German raider Emden is sunk by the Australian cruiser HMAS Sydney; the Germans defeat a British invasion of German East Africa at the Battle of Tanga
December: British and German soldiers declare an informal Christmas Truce amidst the deadlock of the Western Front
1915
March: The Allied naval attack on the Dardanelles commences; the Russians take Przemysl; the British attack on the Western Front at Neuve Chapelle
April: Italy signs the Treaty of London and agrees to join the war on the Allied side; Allied troops land at Gallipoli; the Germans use poison gas during the Battle of Ypres
May: The British passenger ship Lusitania is sunk by a German U-boat; the first Zeppelin raid on London takes place
September: The Russian Tsar, Nicholas II, takes sole command of the Russian army
October: Allied troops land at Salonika; British nurse Edith Cavell is executed in Brussels by the Germans; Bulgaria enters the war on Germany’s side
October‒November: Austria-Hungary crushes Serbia
1916
February: Britain introduces conscription; the Germans attack at Verdun
April: The British surrender at Kut al-Amarah, in Mesopotamia; the Easter Rising takes place in Dublin
31 May: The British and German fleets fight the indecisive Battle of Jutland off the coast of Denmark
June: The Russian Brusilov Offensive breaks through Austrian lines in Poland; the Arab Revolt against Turkish rule begins
1 July: The Allies attack the Germans on the opening day of the Battle of the Somme
August: Romania enters the war on the Allied side but is quickly defeated
September: The British use tanks for the first time, in the Battle of the Somme
December: David Lloyd George becomes the British Prime Minister
1917
January: The French General Nivelle launches his disastrous offensive
February: The Russian Revolution overthrows Tsar Nicholas II
April: Canadian troops take Vimy Ridge; the United States enters the war; after the failure of General Nivelle’s offensive, the French army mutinies
June: The British take Messines Ridge; German bomber attacks are made on London
July: The Kerensky Offensive – Russia’s last attack of the war – fails
October: The British attack at Passchendaele; the Italians are defeated by the Austro-Hungarian army at Caporetto; the Bolshevik Revolution in Russia begins
November: The British launch the first massed tank attack, against the Germans, at the Battle of Cambrai
December: The British take Jerusalem from the Turks
1918
January: US President Woodrow Wilson outlines his Fourteen Points for peace
March: The German Spring Offensive (The Kaiser Battle) begins; the Treaty of Brest-Litovsk confirms Russian withdrawal from the war
July: The German advance towards Paris is stopped at the River Marne
August: The British attack at Amiens and push the Germans back to the Hindenburg Line
September: French and American attacks on German positions take place in the Meuse-Argonne region
October: The Italians attack the Austro-Hungarians successfully at Vittorio Veneto; the British defeat the Turks at the Battle of Megiddo and conquer Palestine
November: The German Kaiser, Wilhelm II, abdicates; an armistice is agreed between the Germans and the Allied commander, Marshal Foch
1919
January: The Paris Peace Conference opens
28 June: Germany signs the Treaty of Versailles
