Most Lethal Weapons - S1.E2

Throughout human history, mankind has strived to create new and inventive ways of killing. Countries conquered and empires shattered on the backs of the most lethal weapons of the ancient world. From the ancient napalm, Greek Fire, to the weapon that helped the Mongols create the largest ancient empire, the composite bow; the speedy battlefield chariot which changed battle tactics, to the simple yet effective caltrop still in use by militaries today, which Top 10 deadly weapon will blow apart the competition and claim the spot of most game-changing?