[32]

Civil War
Harrison during the Battle of Resaca leading the 70th Indiana, May 1864; Harrison was a colonel at the time.
Brigadier General Harrison (left) with other commanders of the XX Corps, 1865
In 1862, President Abraham Lincoln issued a call for more recruits for the Union Army; Harrison wanted to enlist, but worried about how to support his young family.[33] While visiting Governor Oliver Morton, Harrison found him distressed over the shortage of men answering the latest call. Harrison told the governor, "If I can be of any service, I will go."[34]
Morton asked Harrison if he could help recruit a regiment, although he would not ask him to serve. Harrison recruited throughout northern Indiana to raise a regiment. Morton offered him the command, but Harrison declined, as he had no military experience. He was initially commissioned as a captain and company commander on July 22, 1862. Morton commissioned Harrison as a colonel on August 7, 1862, and the newly formed 70th Indiana was mustered into federal service on August 12, 1862. Once mustered, the regiment left Indiana to join the Union Army at Louisville, Kentucky.