On 17 June 1940 Raja enlisted in the ranks of the 11th (Madras) battalion, Indian Territorial Force then on 28 July 1940 was granted a viceroy's commission in the rank of Jemadar in the same unit.[2] The battalion was converted to a regular battalion of the British Indian Army on 15 September 1941 titled the 1st Battalion, 3rd Madras Regiment.[3] On 21 December 1941 Raja received an emergency commission as a second lieutenant in the 3rd Madras Regiment in the British Indian Army.[4]
Raja fought in the Burma campaign and qualified as a paratrooper, choosing to wear a parachutist badge throughout the rest of his career. Following the end of the war, he studied at a military staff college in India.[1] In 1946 he was granted a regular Indian Army commission. [5] Following India's independence in 1947, he was made commander of a battalion in the Indian Army.[1] He commanded the 1st Battalion of the Madras Regiment with the rank of lieutenant colonel during the Indo-Pakistani War of 1947–1948.[6]
In the spring of 1961 Raja led a 4,500 strong contingent,[1] the Indian Independent Brigade Group, to the Republic of the Congo to serve as a peacekeeping force in the United Nations Operation in the Congo (ONUC).[7] On 5 August 1961 ONUC created an independent Katanga Command under Raja headquartered in Élisabethville.[8] On 28 August he led ONUC forces in conducting Operation Rum Punch, and action to detain and deport mercenaries and foreign military personnel serving in the Katangese Gendarmerie.[9] He returned to India with his brigade in April 1962.[10]