The 5th Battalion was reformed in 1939 as a 2nd Line duplicate of the 4th Battalion when the Territorial Army was doubled in size. Initially, the 5th Buffs was assigned to the 37th Infantry Brigade, part of the 12th (Eastern) Infantry Division, which was a 2nd Line duplicate of the 44th (Home Counties) Division. However, on 26 October 1939, it was transferred to the Division's 36th Infantry Brigade in exchange for the 2/6th East Surreys. The 5th Buffs, along with the 6th and 7th Royal West Kents, remained in the 36th Brigade for the rest of the war. Like the 2nd and 4th Battalions, it served with the BEF in France in 1940 and fought in the Battle of France and was evacuated at Dunkirk. The 12th Division suffered heavy casualties due mainly to most of the men having little training and the division having no artillery or support units. After returning to England, the division was disbanded in July 1940, due to the casualties it had sustained. In 1942, the 36th Brigade was assigned to the newly raised 78th Division and took part in Operation Torch, the Allied landings in North Africa, followed by the campaign in Tunisia, where the 78th Division, as part of the British First Army, distinguished itself during the crucial capture of Longstop Hill. The division then fought in the Sicilian Campaign, as part of the British Eighth Army. The 5th Buffs and the rest of 78th Division then took part in the fighting in Italy and served there until the 1945 Offensive.