S1, E4: Some weapons have changed the course of wars through their accuracy, their speed, or their power. Others have made their mark simply because of their ease-of-use, allowing ordinary people to take the fight to empires and nations, and sometimes even win. Join an international team of experts as they look at three key weapons—the pike, the crossbow, and the AK-47 rifle—used by civilians, rebels, and terrorists against seemingly invincible foes.