There is even a hint that Falstaff was originally Oldcastle in "The Merry Wives of Windsor" too. When the First Folio and quarto texts of that play are compared, it appears that the joke in V,v,85–90 is that Oldcastle/Falstaff incriminates himself by calling out the first letter of his name, "O, O, O!," when his fingertips are singed with candles—which of course works for "Oldcastle" but not "Falstaff." There is also the "castle" reference in IV,v,6 of the same play. The name Falstaff was derived from Sir John Fastolf, who was also a historical person—allegedly a greedy and grasping individual, who had a (probably undeserved) reputation for cowardice at the Battle of Patay in 1429. Fastolf, however, died without descendants, making him safe for a playwright's use. He had already appeared as a cowardly knight in Henry VI, part 1.