Kammala jumla mai zuwa: Macdonald ya shiga cikin Rifles na Sarauniya na Kanada a ranar 13 ga Oktoba 1868 a matsayin Rifleman. Ya shafe lokacin rani na 1866 tare da 14th Battalion Volunteer Militia Rifles kusa da Cornwall, a cikin tsammanin wani
mamayewar Fenian. Ya tashi zuwa matsayin Sergeant kafin a ba shi izini a matsayin Ensign a ranar 22 ga Afrilu 1870. Daga nan Macdonald ya shiga cikin tafiyar Colonel Garnet Joseph Wolseley kuma ya yi tafiya zuwa ƙauyen Red River a Manitoba. An kafa tawagar Wolseley ne don murkushe tawayen Red River na Louis Riel. Bayan ya shiga cikin kamawar Upper Fort Garry ba tare da zubar da jini ba (bayan tafiyar Riel) ya koma Toronto, amma zai shiga cikin kawar da tawayen Riel na biyu. Ya yi ritaya daga QOR a ranar 26 ga Afrilu 1882 kuma ya koma Winnipeg. A lokacin tawayen Arewa maso Yamma a 1885, Macdonald ya yi aiki a matsayin laftana a cikin 90th (Winnipeg) Battalion of Rifles, wani sashi wanda ya taimaka wajen tsarawa. Daga baya ya yi yaƙi a Fish Creek a Saskatchewan.