One of the most intriguing American writers about war is the long forgotten Robert Lowry. His novels Casualty and Find Me In Fire and a lot of short stories and some poems are about damage caused by war. Unlike Vonnegut or Heller he is neither ironic nor sarcastic but compassionate.
Lowry's not really been an Anti-war writer. He wanted to become an Officer in 1943.
Out of print in the US since about 1962 - and no American publisher dares to publish any of his works - you can find some of his stories online (www.robertlowry.de).
There's a lengthy article on the web, too: Robert Lowry: An American Tragedy (http:///www.robertlowry.de/jeyes.htm).