Despite the severity of his injury, Colman was able to return to service with the regiment and participated in the Vicksburg campaign in the spring of 1863. He was present at the Battle of Jackson, Mississippi, and was wounded again at the Battle of Champion Hill. After his second wound, he transitioned to the Veteran Reserve Corps and participated in the recruiting service, first with a recruiting station in Fond du Lac, Wisconsin, then at Madison, Wisconsin, and St. Louis, Missouri, before being sent to Washington, D.C., where he served on the Examining Board.