Siege Onagers flatten a pack of archers with a single shot.
Make sure you do both armor upgrades though. By far the easiest way to decimate an army of Longbowmen. At 70 HP this means Huskarls stand 70 volleys before going down. A solid combo, but not impossible to counter at all. How do you counter massed Longbowmen? This has to be the single most asked question on Age of Empires 2 forums amongst new players.
