Johnson's Island is a island in Sandusky Bay, located on the coast of Lake Erie, 3 miles (5 km) from the city of Sandusky, Ohio. It was the site of a prisoner-of-war camp for Confederate officers captured during the American Civil War. Johnson's Island was the only Union prison exclusively for Southern officers but it also held regular soldiers. During its three years of operation, more than 15,000 men were incarcerated there.