In the American Civil War, he was a colonel in the 33rd Iowa Volunteer Infantry which was mustered into U.S. Army service on October 4, 1862 within Mahaska County. He fought to open the Yazoo River for navigation, and then he commanded the 2nd Brigade, 13th Division, XIII Corps at Helena, Arkansas. In August 1863, he was appointed Brigadier General, U.S. Volunteers. On April 30, 1864 at Jenkins' Ferry, Arkansas, he was mortally wounded and then was returned to his home state of Iowa. He died at Oskaloosa, Iowa, July 6, 1864 and was interred at Forest Cemetery in Oskaloosa.