After the Second World War, the security of the nation was once again endangered. This time the threat came from the Malayan Communist Party who was against the British. Part of this group came from Malayan Peoples Anti Japanese Army (MPAJA) who was ordered by the British to surrender and hand over their weapons after the Japanese admit defeat, but they refused to do so. On the other hand, they withdrew and hid in the jungles, and instigated the citizens to oppose the British rule. Several incidents such as the attack and murder of citizens, destructions of rubber estates, burning of buses and vehicles were committed irresponsibly by this group. The British government was forced to declare Emergency in the country on 8 June 1948.
When the Emergency was declared, the Royal Malay Regiment had three battalions. They fought the communist insurgents together with the British and Commonwealth Forces, and the police. The Royal Malay grew to 7 battalions by 1956. At the same time, the Cavalry (Armour) Corps and the Signal Regiment was established. With the establishment of these new regiments, the expansion of the Malaysian Army took a new turn whereby the other races were given the opportunity to join ranks with the Malays to defend the country. Later the Engineers Regiment was established followed by the Military Police Corps. With this additional strength, the Malaysian Army enjoyed success after success until the communists insurgents were wiped out. The Emergency ended in 1960.
When the nation achieved independence on 31 August 1957, the Army expanded rapidly to fill the positions left vacant with the withdrawal of the British and Commonwealth Forces. By 1961, the Royal Malay Regiment grew to 11 battalions. Besides that, the General Service Corps, Service Corps, Ordnance Corps, Electrical Mechanical Engineer Corps were established to meet the demands and needs of the expanding Army. These new units provided the necessary and appropriate service support required to the Infantry units which helped wipe out the remaining communist insurgents.