If you compare Sargent to the War art of Stanley Spencer, Stylistically they're poles apart, but not (I think) by intent.
Or the post-war cartoons of Grotz.
I think at root, all of them are trying to say "this is what the war cost"
There's a super portrait group of the war leaders in the National Portrait Gallery in London. I'm amazed it hasn't been mutilated by now. And.. guess who painted it...
https://www.npg.org.uk/collections/search/portrait/mw00108/G...