Living in Des Moines, Iowa, Isaac enlisted in the 39th Iowa Infantry Regiment, Company B, on August 14, 1862. During the civil war, he fought in battles at Parker's Crossroads in Tennessee, Cherokee Station in Alabama, Resaca and Allatoon Pass in Georgia, in Columbia, South Carolina and Bentonville, North Carolina. He also marched with Union Forces led by General Sherman from Atlanta, Georgia to the sea. He was mustered out of service June 5, 1865 in Washington, D. C. and moved west to Danville, Kansas. On September 17, 1893, he made the land run into Oklahoma Territory and staked a claim northeast of Nash, Oklahoma.