The British 42nd (East Lancashire) Division was a Territorial Armydivision. Originally called the 'East Lancashire Division', it was redesignated as the 42nd Division in 1915. It was the first Territorial division to be sent overseas during the First World War. The division fought at Gallipoli, in the Sinai desert and on the Western Front in France.
The division was sent to Egypt in September 1914 to protect the Suez Canal from Turkish attack. In early May 1915 the division was sent to Cape Helles following the failure of the Allies to achieve the anticipated swift success at Gallipoli during April. The 125th Brigade landed in time to participate in the Second Battle of Krithia on May 6. The entire division was involved in the Third Battle of Krithia on June 4.
The division carried out the Helles diversion at the start of the Battle of Sari Bair in what became known as the Battle of Krithia Vineyard. It remained at Gallipoli until the final evacuation of Helles in January 1916 but was severely depleted by casualties and illness.
After the evacuation of Gallipoli, the division returned to Egypt and participated in the advance across the Sinai without becoming seriously engaged in the fighting.
The British 7th Division was a Regular Army division that was formed by combining battalions returning from outposts in the British Empire at the outbreak of the France on 6 October, 1914.
The 16th (Irish) Division was a division of the New Army, raised in Ireland from the Irish National Volunteers in September 1914 as part of the K2 Army Group.
The British 61st (2nd South Midland) Division was a second-line Territorial Army division raised in 1915 as a reserve for the first-line battalions of the 48th (South Midland) Division.