Timeline of events related to the Battle of the Somme:

1914

June 28 - Archduke Franz Ferdinand, heir to the throne of the Austro-Hungarian Empire, assassinated in Sarajevo, beginning events which lead to a general European war.

August 4 - Britain declares war after Germany invades neutral Belgium.

August 5 - Lord Kitchener becomes Britain's Secretary of State for War and launches mass recruitment campaign.

August 28-29 - Fighting on Somme during French retreat.

September 22-27 - Fighting near the town of Albert during the "race to the sea".

1915

February 19 - British naval attack in the Dardanelles, Turkey begins.

April 25 - Start of the Gallipoli campaign.

Late 1915 - General Sir Douglas Haig becomes commander-in-chief of British Expeditionary Force. Allied conference at which an offensive on the Somme is agreed.

1916

February 21 - German bombardment of Verdun begins.

May 19 - German attack on Verdun forces French to divert troops from Somme.

May 31 - Battle of Jutland inflicts major damage on German navy.

June 24 - Allied bombardment at the Somme begins.

June 29 - Heavy rain forces postponement of attack.

July 1 - Battle of the Somme begins. French troops advance, but British forces suffer almost 20,000 men dead in one day.

July 14 - Renewed British assault. South African troops begin attack on Delville Wood.

July 23 - British and Commonwealth attack on key Guillemont-Pozieres area begins. Australians capture Pozieres two days later.

September 3 - Renewed British attack in northern section of Somme battlefield.

September 15 - Tanks used in battle for first time in history.

September 26 - Joint Franco-British offensive. Thiepval finally taken.

October 7 - Rain delays further Allied advances, leading to a renewed war of attrition.

November 18 - End of Somme offensive.

1917

March 16 - Germans withdraw from the Somme to Hindenburg Line.

1918

March 21 - Beginning of new German offensive which led to renewed fighting on the Somme.

August 8 - Allied counter-offensive, later referred to as the "Black day of the German Army".

November 11 - Armistice.