Entrenching battalions
Entrenching battalions were temporary units formed in the British Army during the First World War. Allocated at Corps level, they were used as pools of men, from which drafts of replacements could be drawn by conventional infantry battalions. The practice ceased on the Western Front by autumn 1917, due to manpower shortages, but saw a revival at the start of 1918. The reduction in the number of battalions in an infantry brigade (from four to three) resulted in many (under-manned) infantry battalions being disbanded. Following the disbandment of these infantry battalions in February 1918, the pool of  men was used to bring the remaining battalions up to strength, and to allocate any remaining manpower surplus to 25 entrenching battalions. These battalions were put to use in improving the existing defences in anticipation of a German offensive, and could be used as a reserve force if needed. The entrenching battalions were disbanded in April 1918, with their troops apportioned to infantry battalions to make good the losses suffered following Operation Michael, which began the German spring offensive of 1918. Many of their war diaries from 1918 have survived and can be consulted at the National Archives at Kew  though the 1918 war diaries for the 1st, 6th, 7th, 10th, 13th, 15th and 17th Entrenching Battalions have not survived. In addition to the entrenching battalions of the British Army, there were also entrenching battalions in both the Canadian Expeditionary Force and the Australian Imperial Force (the 1st Anzac Entrenching Battalion). In addition, the New Zealand (Māori) Pioneer Battalion served with the New Zealand Expeditionary Force. Battalions. The following entrenching battalions were formed: