1914
June 28 –
A Serbian named Gavrilo Princip kills Archduke Franz Ferdinand in Sarajevo, the heir apparent to the Austria-Hungarian monarchy.
July 23 –
Serbia is subject to demands from Austria-Hungary for retaliation. Serbia doesn’t comply with requests.
July 28 –
Serbia is at war as a result of Austria-Hungary. Russia starts to gather its forces.
1 August –
Russian-Germany war is declared.
3 August –
Within the framework of the Schlieffen Plan, Germany declares war on France.
4 August –
Belgium is invaded by Germany. Germany is at war with Britain.
23–30 August –
Germany and Russia engage in combat at Tannenberg. The Second Russian Army is defeated by the Germans.
5–12 September –
At the First Battle of the Marne, the British and French successfully block the German army’s advance towards Paris. Four years of trench warfare begin as the Germans dig in.
October 19 to November 22 –
At the First Battle of Ypres, the Allies triumph over the Germans.
2 November
The British start to blockade Germany with their ships.
11 November –
War is declared against the Allies by the Ottoman Empire.
24 December –
At Christmas, there is an unofficial cease-fire between the two sides.
1971
4 February:
Around the island of Britain, the Germans start to utilise submarines against Allied trade ships.
April 25 –
At the Battle of Gallipoli, the Allies assault the Ottoman Empire. The Ottomans will win this battle after more than eight months of fighting, and the Allies will be forced to withdraw.
May 7 –
German submarine sinks the luxurious British passenger ship The Lusitania. 1,195 civilians lost their lives. The United States joins the war against Germany as a result of this atrocity, which causes indignation around the world.
14 October –
By launching an attack on Serbia, Bulgaria joins the conflict.
1916
21 February –
France and Germany start the Battle of Verdun. The French will ultimately prevail in this conflict, which will endure until December of 1916.
May 31 –
Britain and Germany engage in the Battle of Jutland, the largest naval engagement of the war, in the North Sea.
July 1 –
Beginning of the Battle of the Somme. There will be almost 1 million casualties or wounded soldiers.
1917
19 January –
The Zimmerman Telegram, in which Germany asks Mexico to enter the war, is intercepted by the British. The United States will then declare war on Germany as a result of this.
March 8 –
The start of the Russian Revolution. On March 15, Tsar Nicholas II loses his position of authority.
April 6 –
By launching an attack on Germany, the United States joins the conflict.
7 November
The Russian government is overthrown by the Bolsheviks, led by Vladimir Lenin.
17 December –
The Russians decide to end the war and make peace with the Central powers.
1918
8 January –
The “Fourteen Points” of President Woodrow Wilson are made in an effort to bring an end to the conflict.
March 21 –
In order to destroy the Allies before American reinforcements can be sent, Germany starts the Spring Offensive.
July 15 –
The Second Marne Battle starts. The Allies will win this conflict decisively on August 6.
11 November –
At 11 a.m. on the eleventh day of the eleventh month, Germany consents to an armistice, which puts an end to the combat.
1919
June 28 –
Germany ratifies the Treaty of Versailles, bringing an end to World War I.