Comic book character, owned and published by DC Comics. He was created by Robert Kanigher and Joe Kubert in Our Army at War #151 in early 1965.
Nearly always, war comics focus on "the good guys" -- the Allies, the Americans, the British, or someone else fighting an honorable fight against oppressors. Even in Germany, they don't have war comics starring the Nazis, because everyone can agree: Fuck the Nazis. But in the mid-1960s, Kanigher and Kubert decided to create a character based on the German pilots of World War I -- specifically based on Manfred von Richthofen, the Red Baron, the greatest flying ace of the war. In this case, they came up with Hans von Hammer, the Enemy Ace.
An incredibly skilled pilot, Von Hammer was a man of impeccable honor and pride who was nevertheless tormented by the deaths of those who he killed in battle. Like the Red Baron, the "Hammer of Hell" flew a Fokker DR1 triplane; unlike the real-world ace, Von Hammer survived to old age. His adventures were generally a bit formulaic -- Von Hammer and his fellow pilots flew missions, encountered Allied pilots, and defeated them. After returning home, his men would praise their leader, the cold-hearted machine of death, while Von Hammer brooded on his death-haunted existence and on the chivalric life he yearns for. He'd get a few panels to visit one of his only true friends, a wolf on the edge of the Black Forest. And then he was off to fly more missions.
One of his other true friends was a small dog he'd rescued which he names "Schatzi." He even introduced the dog to the wolf, which, luckily accepted Schatzi as a friend instead of eating him. But even his friendship with Schatzi didn't last long, as he accidentally dropped the dog from his plane while flying a mission, which game Von Hammer more opportunities to grieve and brood.
One of the best loved "Enemy Ace" tales was "Silent Night," written and illustrated by John Byrne, with finished art by Andy Kubert, son of Joe Kubert who co-created the character. The story was published in one of DC's Christmas specials in 1988. It was a fully dialogue-free story, inspired by the Christmas truce of 1914. Von Hammer lands his plane at an Allied field hospital, delivers food for a Christmas dinner for the patients, and salutes a posted casualty list. One of the patients threatens to shoot Von Hammer, but another takes the gun away -- and tells the Hammer of Hell it's time to make his exit. It's not a particularly deep story, but it aligns well with the character's description as a decent man haunted by the brutality of war -- and Andy Kubert's finished art making Byrne's art look more like Joe Kubert's is a very nice touch.
DC's war comics rarely brought in superheroes or supervillains -- but in the later years of the series, Von Hammer occasionally faced off with opponents who had codenames and dressed outlandishly -- the Skull Men, the One-Eyed Cat, the Harpy, St. George, a British pilot who flew in a suit of plate armor, and the Hangman, a French ace who was Von Hammer's only recurring opponent.
"Enemy Ace" lost its lead feature slot in "Star Spangled War Stories" in the early 1970s, but Von Hammer was brought back for occasional stories in DC's war comics and also appeared periodically in graphic novels and guest starring roles. In 1990's "Enemy Ace: War Idyll" by George Pratt, it's eventually revealed that Von Hammer lived until 1969, only dying after concluding an interview with a journalist and turning his memoirs over to him.
A later graphic novel, "Enemy Ace: War in Heaven" from 2001, written by Garth Ennis with art by Chris Weston and Russ Heath, has Von Hammer persuaded to fly with the Luftwaffe during World War II. Now piloting a Messerschmitt Bf 109, Von Hammer is no fan of the Nazis, but flies because he's a German patriot. At one point, he crashes near Leningrad and during his hike back to German lines, witnesses many atrocities on the Russian front. And in 1945, he ends up parachuting into Dachau, and what he sees prompts him to persuade his unit to surrender to the Allies -- specifically, Sgt. Rock's Easy Company.