In addition to its existing battalion, the London Irish Rifles (18th Battalion, London Regiment) raised two further Lines, one of which remained as a reserve unit in England throughout the war.
The two Service Battalions served on the Western Front from 1915 onwards and in Greece and Palestine from 1916 to 1918.
At the outbreak of war, they were based in London and became part of 5th London Brigade, 2nd London Division.
The battalion landed in France during March 1915, and became 141st Brigade in (the renamed) 47th (2nd London) Division during May 1915.
The 141st Brigade served on the Western Front for three and a half years and ended its war near Lille.
They were formed in August 1914 and later joined 2/5th London Brigade, 2/2nd London Division at Reigate.
The brigade was retitled 180th Brigade, 60th (2/2nd London) Division and landed in France during June 1916. After four months in the line near Vimy, the Division moved to Salonika in November 1916.
In July 1917, they moved to Egypt and then later in the year onto Palestine and Transjordan. The battalion remained in 60th Division during the early part of 1918 but, in July, were disbanded in Palestine, with its men going to units within 10th (Irish) Division.
1,087 men from the London Irish Rifles are listed in the CWGC database of First World War deaths: