after the war, the 370th infantry reverted to its prewar status as the 8th illinois infantry, and duncan was promoted on march 18, 1919, to the rank of colonel and commander of the regiment. the regiment was stationed at springfield's camp lincoln. in february 2017, authorities announced the discovery of a post-world war i 8th illinois collar disc, a service unit insignia artifact connected to the date of col. duncan's command.