And while fighting the Parthians, he is killed. Crassus is killed while fighting the Parthians, which breaks up this first triumvirate, and then Pompey switches sides. He switches sides over to the conservative side. So now, instead of being one of Julius Caesar's allies, he becomes one of his opponents. And so Julius Caesar, he's victorious. He's able to conquer these powerful Gallic tribes. Plutarch, according to him, Julius Caesar's legions fought over, or on the order of three million Gauls.