Moral laws of war
In 1916 there was a proposed Amendment to the US Constitution that would put all acts of war to a national vote, and anyone voting yes would have to register as a volunteer for service in the United States Army. https://www.huffingtonpost.com/2013/09/04/amendment-war-national-vote_n_3866686.html?utm_source=reddit.com 
There's no just war unless your life or property is under attack.