Why then did war happen happily in the millennia in which money supply was almost entirely limited? Governments have the ability to buy currency if they can't/d

Why then did war happen happily in the millennia in which money supply was almost entirely limited? Governments have the ability to buy currency if they can't/don't want to mint new coin. For example, states have been issuing various forms of bonds to raise money for war since at least the 1600s.