Operation Manifest Climax

Operation Manifest Climax was a brutal, apocalyptic war of conquest waged by the Republican Union against all of South America, which was mostly unified into the so-called Neutrality Pact. While the Union would eventually claim victory and proclaim the New United States of America, troops would continue fighting and dying into the indefinite future. At the time, Manifest Climax was the most deadly war in human history. 
Marcus Aurelius Arkham Custer-Steele, son and presumed heir of Union President Joe Steele, was shot down in suspicious circumstances over the jungle in 1941. Chuck Oswald was the only surviving member of the squadron.