Alexander Crosman peered through his telescope from the deck of his Union Army gunboat. What the commander of the USS Somerset saw bewildered him. Nearly 18 miles from shore, off the Confederate-held city of Apalachicola, Florida, Crosman watched two men standing in a small skiff and waving frantically at the military ship. Crosman ordered his ship’s guns leveled and an armed guard on deck.

As the skiff drew closer, he looked down at the men. They were skeletal, naked excepting only rags for pants and vests made of moss. Their skin was bruised, raw, and bleeding from sores and cuts, covered with insect bites and blisters. The naval officer barked, “Who in hell are you, and what are you paddling under my guns in this manner for?” Their parched throats could barely gasp the words out. What they said shocked Crosman.

They claimed to be Federal soldiers, privates from Ohio. Their army was battling rebel forces in Tennessee, some 500 miles away. Thinking they were deserters, Crosman growled that they were a “damned long ways from camp.” Not deserters, they insisted—escapees. They were secret infiltrators behind enemy lines, part of the now famous Great Locomotive Chase, a daring but ill-fated raid Union forces hoped would cut the Southern rebellion’s throat.