He served one term in the Wisconsin State Assembly, representing Marquette County, and was a Union Army surgeon throughout the American Civil War.
[1][2] During the American Civil War, Mitchell was the assistant surgeon of the 10th Wisconsin Infantry Regiment for two years and was at the Battles of Perryville and Stones River.
In 1874, he was elected to represent Marquette County in the Assembly's 1875 session, receiving 776 votes to 654 for Democrat Neil Dimond.
[3] Mitchell was defeated when he ran for re-election in the 1876 assembly, with 507 votes to 673 for Democrat B. Frank Goodell.
[5] Mitchell spent many years on the Board of Examining Surgeons for the United States Pension Department in Portage, retaining that position through several changes of national government.