On May 6, 1861, at the outbreak of the Civil War, he enlisted as a private in Company E, 2nd Iowa Volunteer Infantry Regiment.

He took part in the battles of Fort Donelson, Shiloh, Corinth, Bear Creek, Resaca and Oostanaula River.

In 1878, McCoid was first elected as a Republican to represent Iowa's 1st congressional district in the U.S. House.

He was an unsuccessful candidate for the Republican renomination in 1884, losing to John S. Woolson, who then lost in the general election to Democrat Benton Jay Hall.

This article incorporates public domain material from the Biographical Directory of the United States Congress