Henry Wirz
Heinrich Hartmann Wirz better known as Henry Wirz was a Swissborn Confederate officer in the American Civil War. He is best known for his command of Camp Sumter, the Confederate prisonerofwar camp near Andersonville, Georgia he was tried and executed after the war for conspiracy and murder relating to his command of the camp.
Eleven days after the execution, it was claimed that the star witness from the trial had perjured himself. He was not Felix de la Baume from France, but Felix Oeser, born in Saxony, Prussia. He was actually a deserter from the 7th New York Volunteers.
Source: Wikipedia