[11] Jayal became the first Indian officer to be posted in the 6th Battalion of the 13th Frontier Force Regiment, earlier known as 59th Scinde Rifles.

[12][13] He served alongside Anant Singh Pathania and Bakhtiar Rana in the Waziristan Campaign of 1936-39, among other young (then) Indian officers of the 6/13 FFR.

[1] In the rank of major, Jayal was awarded the Distinguished Service Order (DSO) for displaying 'conspicuous bravery and military skill' against the Italians at the Barentu Road in Eritrea in January 1941, in the East African Campaign.

[16] In the rank of brigadier, Jayal commanded the 80 Infantry Brigade of the Indian Army during the Indo-Pakistan War of 1947-48.

[19][20] After retiring with the rank of brigadier, over the late 1950s-early 1960s, Jayal served as Director of Military Training and Social Service in the Government of Uttar Pradesh state, India.