The 31st Infantry Brigade was an infantry formation of the British Army, which participated in both the First and the Second World Wars. The brigade was later reformed after the end of the war serving in the British Army of the Rhine until the end of National Service in 1956, which saw the reorganisation of the brigade as the 11th Infantry Brigade.

The 10th (Irish) Division, was one of the first of Kitchener's New Army K1 Army Group divisions, authorized on 21 August 1914, after the outbreak of the Great War. It included battalions from the various provinces of Ireland. It was led by Irish General Bryan Mahon and fought at Gallipoli, Salonika and Palestine. It was the first of the Irish Divisions to take to the field and was the most travelled of the Irish formations. The division served as a formation of the United Kingdom's British Army during World War I.