In May 1861, Dosch enlisted as a member of General John C. Frémont's body guard and served under Frémont until October 25, 1861, when Dosch was wounded in the right leg during the Battle of Springfield. In March 1862, Dosch was accepted as a member of Company C, Fifth Missouri Cavalry. Dosch was promoted to sergeant of Company C, then sergeant-major of the regiment and then adjutant, and for the last three months he was acting colonel. On the consolidation of the two regiments in 1863, he resigned his position and retired from the service.
