Following the success of the "Lyme" and "Unicorn" in 1748, the mid-century period saw the simultaneous introduction in 1756 both of sixth-rate frigates of 28 guns (with a main battery of 24 nine-pounder guns, plus four lesser guns mounted on the quarterdeck and/or forecastle) and of fifth-rate frigates of 32 or 36 guns (with a main battery of 26 12-pounder guns, plus six or ten lesser guns mounted on the quarterdeck and/or forecastle).