From 6 November 1941 the division came under the command of Lieutenant-General Renya Mutaguchi and was reassigned to the IJA 25th Army (which was under the command of General Yamashita Tomoyuki). It participated in the invasion of Malaya and Singapore. The 124th Infantry Regiment and some other units of the 18th Division took part in the Battle of Borneo from 16 December 1941 on. Following the conquest of Singapore, the division was transferred to the IJA 15th Army for the invasion of Burma, where it suffered over 3000 casualties, primarily from malnutrition and malaria in securing control of the Ledo Road. The supply situation was so bad that some elements of the division stole rations and weapons from the stores of 53rd division, in Tanai Township earning for themselves the nickname of "thief troopers".