Is war ever a moral choice?

In January, 2025, the Allnonfiction online book discussion group has been discussing The Demon Of Unrest by Erik Larson which describes the events and dynamics that occurred just before the beginning of the US Civil War in 1861.

We learned that there were some groups in the Confederate states which opposed the war and even joined with the Union. One of the group members, Becky, pointed out that there has been opposition to most wars whether it was the revolutionary war, the World Wars, Vietnam, etc. During this discussion I posted the following ideas and want to also raise the question with my substack readers “When is war, if ever, a moral decision and action?”

Thank you Becky for the information about the people or groups who oppose the popular support for war no matter where the conflicts have occurred.

"History is written by the victors " the slogan goes and so we don't learn much about the ones who opposed the majority support for war. This observation raises the question about the morality of war and reminds me of the Roman Catholic teaching about "just war" theory. What is a just war? When is the deliberate and intentional killing of our fellow human beings justified?

Humankind has been slowly evolving from our ethnocentric warrior phase to a more world centric view of modernism where who is right isn't as important as what is right. Which raises the question in these moral dilemmas of what is the right thing and how do we discern what is right?

The confederate states were trying to preserve an economic system and way of life based on enslaving other human beings. In order to do this they wanted to secede from the country they had been united with. Is this a moral thing to do? What if the union states had allowed the slave states to just secede and form their own country? How do you think this might have worked out?