at first, I though you were talking about William IV, but he wasn’t George III’s brother, he was his son. So what does George III’s brother have to do with this?
He was George 4th brother and George 3rd’s son he who list to George Washington who was the first president and not George Clinton who was just in charge of parliament.
He who list to George Washington? Anyway, I got confused because you originally said
George the 3rd and his brother William
Thus I though you were talking about a brother of George III, and not William IV.