A Royal Malaysian Air Force airfield - RMAF Butterworth - is located to the north of Butterworth proper. Completed by the British in 1941 just prior to the Japanese invasion of Malaya, the airfield served both the Royal Air Force and Royal Australian Air Force squadrons tasked with defending the airspace over Penang. However, the Japanese immediately gained air superiority, damaging the Butterworth airfield in the process. The station was then captured by the Imperial Japanese 25th Army on 20 December 1941.