Moving rapidly and with determination. “Hell” in this case strengthens the word “bent,” which means a direct route (although it sounds as though it should mean the opposite). “Leather” refers either to a saddle or to a whip used to urge a horse to move faster, or perhaps items. “Hell for leather” meaning “all deliberate haste” was a popular phrase in itself. Among a number of variants is “hell-bent for election,” said to have originated with the 1840 Maine gubernatorial race and appearing in an 1899 Stephen Crane story: “One puncher racin' his cow-pony hell-bent-for-election down Main Street.” Others are “hell-bent for breakfast,” “for Sunday,” and “for Georgia.”