From 24 November to 2 December 1920, Kanayan was the Defence Minister of the short-lived First Republic of Armenia and commanded Armenian troops in various successful wars. The last battles against the Ottoman Empire at the Caucasus Campaign essentially saved the Armenian Republic from total destruction. As a Defence Minister before the end of 1918, he took responsibility at the Armenian–Azerbaijani War and Georgian–Armenian War. Later in 1920, Turkish–Armenian War. In 1920, after the establishment of the Soviet regime in Armenia, Drastamat Kanayan remained in the country. He was exiled with 1,200 officers of the Republican army in January 1921; he later went to Moscow, finally settling in Romania in 1925.