The 1st Battalion, which had originally been serving with 25th Infantry Brigade in the 50th Division, was sent to France in early 1940 to join the rest of the British Expeditionary Force. The battalion fought in the Battle of Dunkirk and was forced to be evacuated. After Dunkirk, the battalion became part of the 210th Independent Infantry Brigade (Home), which was later renumbered the 38th (Irish) Brigade. The brigade was initially attached to the 6th Armoured Division and served with them during the start of the Tunisian Campaign until 2 February 1943, when it was exchanged with the 1st Guards Brigade of the 78th "Battleaxe" Division. The battalion would remain with the division for the rest of the war, serving in the fighting in Sicily, where the Irish Brigade fought, with great success, in the Battle of Centuripe in August 1943. The success in Sicily was followed by the landings in the Italian mainland. During its service in Italy, the battalion took part in many river crossings and battles with perhaps the most famous being the Battle of Monte Cassino, one of the hardest-fought battles of the entire campaign and saw their final battle in Operation Grapeshot.