The actual historical basis for Heston's character in the film.
"Shut up!" he explained.
Heston's character is based on Captain - eventually Lt. Gen., John Twiggs Myers, who received the Medal of Honor for his role in defending the legations. Fort Myers Florida was named after his father, Captain Abraham Myers (US Army - later Colonel in the Confederate army)
His maternal grandfather was Gen. David Twiggs, a hero of the Mexican War who defected to the Confederacy at the start of the Civil war.