Percy was a major in the 3rd Battalion of the Northumberland Fusiliers from 1886 to 1895, and was appointed in command of the "Tyne Volunteer Infantry Brigade" 5 March 1902 with the rank of Colonel in the Volunteer Force whilst so serving.
Percy was a major in the 3rd (Militia) Battalion of the Northumberland Fusiliers from 1886, and was promoted to lieutenant-colonel on 15 July 1895. He was appointed in command of the "Tyne Volunteer Infantry Brigade" on 5 March 1902, with the rank of colonel in the Volunteer Force whilst so serving.