In 1921–22, a major reorganization was undertaken in the British Indian Army leading to the formation of large infantry groups of four to six battalions. Among these was the 15th Punjab Regiment, formed by grouping the 27th Punjabis with the 25th, 26th, 28th and 29th Punjabis. The battalion's new designation was 3rd Battalion 15th Punjab Regiment. During the Second World War, the battalion served in British Somaliland, Aden, Persia, Iraq, Syria and Italy. It was converted into a Machine-Gun Battalion in 1946. In 1947, the 15th Punjab Regiment was allocated to Pakistan Army. In 1956, it was merged with the 1st, 14th and 16th Punjab Regiments to form one large Punjab Regiment, and 3/15th Punjab was redesignated as 11 Punjab. During the Indo-Pakistani War of 1965, it was deployed in the Sylhet Sector of East Pakistan, while in 1971, it served in the Shakargarh Sector.