The most famous of Captain Americas part-time demises was his first. Steve Rogers first appeared in the pre-Marvel era, a character whose debut saw him punching Hitler square in the jaw a good few months before the US had even entered the war. His adventures actually continued past 1945, with the Star-Spangled Man moving onto Commies instead of Nazis. Of course, eventually Cap fell out of favour during the mid-fifties (when superheroes reached an all-time low in popularity and would mostly supplanted by sci-fi and horror books), and wasnt killed off but his title did get cancelled. It wasnt until a decade later Stan Lee thought to bring him back in the pages of Avengers #4, 1964. Its there that Lee also retconned Captain America's history so that Cap didnt fight past World War II, and was in fact missing, presumed dead after a botched attack on Hydra villain Baron Zemo saw him and teen sidekick Bucky aboard a drone plane full of explosives headed for the US. They knocked it off course, but supposedly died in the crash.