After the First World War, the 51st Sikhs were grouped with the 52nd, 53rd and 54th Sikhs, and the two battalions of Guides Infantry to form the 12th Frontier Force Regiment in 1922. The 51st Sikhs became 1st Battalion (Prince of Wales's Own Sikhs) of the new regiment. During the Second World War, 1 FF saw active service in Iraq and Syria before moving in 1943 to Italy, where it again served with distinction. In 1947, the Frontier Force Regiment was allotted to Pakistan Army. In 1956, the Frontier Force Regiment, Frontier Force Rifles and the Pathan Regiment were merged into the Frontier Force Regiment, and 1 FF (Prince of Wales's Own) was redesignated as 3 FF. During the Indo-Pakistan War of 1965, the battalion fought in the Battle of Chawinda, while during the Indo-Pakistan War of 1971 it participated in the Battle of Chhamb in Kashmir.