John H. Stibbs rose from captain to lieutenant colonel of the 12th Iowa Infantry, serving through the battles of Fort Donelson, Shiloh, Vicksburg, and the 1864 engagement at Tupelo, eventually commanding six companies of the regiment. In January 1865 he was summoned to Washington, D.C., to sit on the military commission that tried Confederate Captain Henry Wirz for war crimes committed at Andersonville prison, one of the war’s most notorious atrocities.