Main events of 1917

February 3 – the USA severs diplomatic relations with Germany as German U-boats threaten US shipping, and intelligence suggests that Germany is provoking Mexico into a war with the USA.

February 25 – German troops withdraw 25 miles along part of the front to establish stronger defensive positions.

March 15 – The Russian Revolution causes Tsar Nicholas II to abdicate.

April 6 – The USA declares war on Germany.

April 9 – The Battle of Arras. New tactics are successfully employed by the British.

April 16 – The Second Battle of Aisne begins with large loss of life, which starts mutinies within the French Army.

June 7 – Battle of Messines Ridge. Mines are detonated under the German positions and the explosions are heard in Britain.

June 13 – German aircraft bomb London, killing 162 people and injuring 432.

June 25 – The first US troops arrive in France.

July 31 – The Third Battle of Ypres begins.

August 20 – The Third Battle of Verdun begins.

October 19 – The last Zeppelin raid on Britain is carried out by 11 airships.