The Merry Wives of Windsor in 1597, after which controversy over the original naming of Falstaff (he was originally the historic Sir John Oldcastle, which presumably did not please Oldcastle's descendants) forced Shakespeare to rename the character. 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. 18 January 1602 was the date the play was entered into the Register of the Stationers Company. The first quarto was
John Oldcastle John Oldcastle, was Herefordshire's MP during the latter part of the reign of King Richard II. Oldcastle is first mentioned in two separate documents in 1400, first as a plaintiff in a suit regarding the advowson of Almeley church, and again as serving as a knight under Lord Grey of Codnor in a military expedition to Scotland. In the next few years Oldcastle held notable positions in the Welsh campaigns of King Henry IV of England against Owain Glyndŵr, including captaincy first over Builth Castle in Brecknockshire and then over Kidwelly. Oldcastle represented Herefordshire as a "knight of the shire"