Mir Dad Khan was born into a prominent family of the ethnic Pashtun Tareen/Tarin clan, settled in village Rehana in the Haripur District of the Hazara region. After some basic schooling, he decided to enroll as a soldier in the (then) 9th Hodson's Horse of the British Indian Army Cavalry, in 1887, as a Sowar.[1] After initial training, was posted to duties at Ambala, Punjab. His first participation in a major military campaign was during the Chitral Expedition circa 1895–97, as a Lance Daffadar. Subsequently, he served in the Tirah Campaign and operations in the Barra Valley, 1897–98.[1] Later, between October 1914 and mid-1915, he served along with his regiment in France in World War I as a Risaldar.
He was invalidated for health reasons in 1915 and returned to India to the regimental depot until the end of the War. He retired in August 1918 and was awarded an Order of British India (2nd class) for long service. During his military service, he represented his regiment at the Delhi Durbars of 1903 and 1911.[2]