More than two hundred years before Jesus was born, on the coast of Spain, an army faced a weapon it feared more than any other. It was a heavy javelin. The shaft was wrapped in rough rope fiber and smeared with pitch. And then they set it on fire and threw it. Now the Roman historian Livy wrote down what made it so terrible. He said it wasn't when it hit the body. It was when it hit the shield. And the reason is that when it kept burning it forced the soldier to throw away his shield and be at the mercy of the sword.