We don’t know precisely why the three white officers on board a Confederate transport and gunboat called the CSS Planter decided to go ashore in Charleston, South Carolina, the night of May 12, 1862.

Maybe they went to see their families. Maybe they went drinking or whoring. Certainly they were acting against orders, but they seemed to think the slave they left in charge of the Planter, a skilled 23-year-old harbor pilot named Robert Smalls, would take good care of the ship for them.

On board were pieces of naval artillery, including a 32-pounder on a pivot, a 24-pounder howitzer, and a gun that had been at Fort Sumter. There were 200 rounds of ammunition, and according to several accounts there was a book of codes and signals that were currently in use by the Confederate Navy. Perhaps most importantly, there was Smalls himself, a true fount of information about Confederate defenses around Charleston harbor.