The Royal New Zealand Infantry Corps was at that time made up of ten separate Infantry Regiments and in 1963 a single Infantry Regiment was formed from the two active regular Infantry Battalions, the 1^st and 2^nd Battalions of the New Zealand Regiment.

In 1965 and 1966, the 1^st Battalion was under operational control of the 19^th United Kingdom and 99^th Gurkha Infantry Brigade and contiuously served with the 28^th Commonwealth Infantry Brigade in Malaysia and Singapore.

Sub-Units of the Battalion were detached for service with the 1^st Australian Task Force in Vietnam from 1967 to 1971, these units were Victor Company and Whiskey Company.

During the Vietnam war, in 1969,  the Regiment moved across the Jahore Straits to Singapore,  to an interim home in Punjab Square Nee Soon Garrison and then in June, 1971 to Dieppe Barracks.

1 RNZIR and the New Zealand Naval and Airforce detachments returned to New Zealand after 32 years of service in Southeast Asia, in 1989.  I RNZIR marched in to its new home at Linton Military Camp.