The 4th/5th Battalion, Suffolk Regiment was a Territorial Army unit and was split to help re-create the 5th Battalion, which had been disbanded in the 1920s, in 1939 due to the Territorial Army being doubled as another conflict had, by this time, seemed inevitable. Both battalions were assigned to the 54th Infantry Brigade, which included the 4th Royal Norfolk Regiment, assigned to the 18th Infantry Division, a 2nd Line duplicate of the 54th (East Anglian) Infantry Division. Despite being a 2nd Line formation, the 18th Division contained many 1st Line units. The division spent the early years of the war in the defence of England and guarding against a possible German invasion after the bulk of the British Army was evacuated at Dunkirk. In late 1941 the 18th Division, the 4th and 5th Suffolks included, were originally to be sent to Egypt but instead were sent to Singapore to help strengthen the garrison there after Japan entered the war in December 1941. In early 1942, both the 4th and 5th battalions fought briefly in the defence of Singapore against the Japanese, with the 18th Division, before British Commonwealth forces on that island surrendered on 15 February 1942 under the orders of Lieutenant-General Arthur Percival. Men from the two battalions suffered great hardship as POWs and were forced to participate in the construction of the Burma Railway.