(This is edited out of some comments on the US Civil War I wrote in Ta-nehisi's Coates blog back in 2012. All comments in that discussion have been taken down, so I am very glad I saved copies!)
I don't have any ideology in this area beyond objecting to the deaths of nearly 100 million and wanting to avoid a catastrophic global war, which seems to me scarcely an ideology at all.
If humans keep on believing that wars are a way to resolve conflicts, which many do, and the wars keep increasing in intensity and scope, as they have, and the weapons and strategies in capability, as they have, then there will be nothing left of human civilization. Opposing that is not idealism but pragmatism.
Regardless of what could have happened in the 19th and 20th century, it is important to continue efforts to make war less and less likely.