 They were instruments of war. And the men who ran in front of his chariots were a part of the armored cavalry. In other words, what he is saying to the people is he is going to institute a draft. You wanted a king to go out and fight for you. Did you think he would do the fighting by himself? Oh, no. He's going to take your sons and your daughters. Now, in the period before this, the army was volunteer, like ours is today.