You be the Judge!
Walker was a so-called “filibuster” that led an unauthorized military expedition to Nicaragua, overthrew the government there, and installed himself as President. While in Nicaragua, he was recognized as Nicaragua’s President by then US President Franklin Pierce, and proceeded to re-legalize slavery there. Unfortunately, he PO’d some powerful folks, including the British Empire, and eventually was overthrown by a coalition of neighboring states.
He was later arrested by the US Navy. He later attempted to return to Central America where he was captured by the Honduran government and executed.
As a side note, P.G.T. Beauregard, who later served as a General in the Confederate Army, at one point had volunteered to resign his US Army Commission and join Walker in the expedition; Senior Officers like General Winfield Scott talked him out of it.
This was not Walker’s only misadventure though. Prior to that, he had raised an Army and attempted to invade Mexico and create a colony there.
Really strange dude.