Great grand nephew of George Washington, Colonel Lewis Washington, had his estates near Harpers Ferry, where he was stationed, and was rumored to have two relics: a sword given to George by Frederick the Great, and a pair of pistols from Marquis De Lafayette. Other prizes were many slaves to be freed and the Colonel himself as a hostage. Brown had sent a detachment under John Cook Jr. to raid the estate a day before the raid on the armory. Cook had befriended the Colonel previously and had noticed the relics while visiting the Colonels estates.

Now I vaguely remembered from the dollops 3-parter that Brown had a window to escape when things started to go bad but delayed because he was waiting for that detachment to return. But Wikipedia says they returned before the raid and had the relics and Lewis hostage with him in the armory. It even claims the buckle of the sword saved him from a saber thrust. So maybe I remembered wrong or maybe that pre raid blew his cover early. But he also let a whole train go after telling everyone on board exactly who he was and what he was going to do.