Arguing morals is like tying cats tails together. Fun, but useless. The structure of morals, ethics, justice are socially adaptive and totally culturally specific. Time, distance, culture all change the specifics. As an example prohibition/temperance was part of a social and moral imperative. Personal rights and the right to choose is equally part of a social and moral imperative. Both are covered by social compacts. Yet each has held sway in time as they go around in circles. Because, morals and ethic are socially adaptive and culturally specific to a particular person and time.

There is no such thing as morals or justice in concrete forms. There are only frameworks that each individual works within and the more generalized the situation the more likely people will agree upon that framework. Law has nothing to do with morals or justice. There have been many unjust laws (racial segregation, Jim Crow laws, poll taxes, being examples). There has been many incidences of the "justice systems" failing to dispense justice and providing a mechanism for violating peoples rights (DNA labs failure to do tests, lying police officers, tainted judges, etc.).

If you maintain a judeo christian anglo saxon north american eastern seaboard upper mid manhattan living above the fifteenth story point of view you might have commonality unless you want to talk about the north facing neighbors versus those hippy sun lovers on the south side of the building. There are so many different forms of ethical construct for considering war and the waging of wars but they all rely on perspective. Whether it is "just war" or "law of war" there are differences in the interpretation of either.

Indigenous populations are great examples of the horrors of colonization. The enforced and unrepresented legal compacts that allowed for American westward expansion and displacement of the Indians is not much different than the United Nations compact that created Israel. Indigenous populations were exploited and disenfranchised.

In capitulation to the ethical and moral dilemmas many people look to the concrete base of laws and religion to inform their decisions. Neither behavioral governing system is without egregious error and both are fraught with social change and temporal defining moments. In other words, you can't look through the lens of history and say this or that war was moral. Well you can but it is a waste of time. You have to put yourself in the people of that period and see if you can perceive their decision process. History is filled with good people, making the best decisions at the time, based on the information they had, and with the capacity they contained, that were evil in the extreme to the successive generations making claims. I'm sure as the sun shines the opposite is likely true too.

Don't even get me started on moral panics.