William Walker: Filibuster and (Fantastically Bad) President

William Walker's grave in the Old Trujillo Cemetery, Trujillo, Colón, Honduras. Scott Raine / Wikipedia

The adventurer and filibuster William Walker was, in his heyday, lauded as an American hero for his repeated failed invasions of areas of Mexico and Nicaragua. But what led this man on a fanatical mission to invade these regions? Perhaps more importantly, why did so many folks in the US support his various strange escapades?