The first facts about Iron Jaw date back to 1917, when he was known as Sergeant Vonn Schmidts in the Kaiser's army. His closest friend was a weasel named Corporal Schicklgruber -- the rat who would later become Der Fuehrer!
"Look, Vonn Schmidts," Schicklgruber pointed out to him from the battlefield foxhole, "Dot is dot stupid Captain Fluger who iss against my political ideas! He could make trouble!"
"Yes, yes, I know!" Vonn Schmidts replied sullenly.
"We attack in two minutes!" announced their captain, eyes focussed on the enemy through a pair of binoculars.
Schicklgruber murmers to his friend, "A lot of people get shot in der back accidentally going over."
Vonn Schmidts folded his arms, "It would be too bad if that happened to der Captain -- look! He is getting read to lead the attack!"
"Charge, men!" Captain Fluger shouted, as he lept out of the foxhole, then falling suddenly as he was shot in the back. "Do you know, Schicklgruber," Vonn Schmidts said, "That I am the best shot in the regiment? Oops! I hit the poor captain by mistake!"
Captain Fluger was mortally wounded but with his last dying strength he hurled a grenade at the evil pair that plotted against him. "You filthy mongrels!"
"Run, Corporal," Vonn Schmidts shouted as he tried to escape, "He is throwing a grenade! He saw us!"
Not moving quickly enough, Vonn Schmidts was caught in the explosion. "C ... come back, S ... Schicklgruber! Help! Save me!" he choked out. But Schicklgruber had no time to waste in saving a wounded friend! He may have felt secretly glad that Vonn Schmidts was out of his way for good! Years passed and by 1933, Schicklgruber had become Der Fuehrer and through his Nazi Party had risen to full control.
It was in 1933 that he sat alone in his study plotting how to conquer the world when he was interrupted by a voice from the past ... "Well, my old friend Schicklgruber! Are you surprised to hear my voice, or had you forgotten Sergeant Vonn Schmidts, who got his jaw shot off while doing you a favor?"
Vonn Schmidts comes out of the shadows, now bearing the terrifying visage of Iron Jaw. "What will people think when they learn your part in the murder of Captain Fluger? But why should you care? You won't live to find out!"
"No! No -- don't kill me!" pleads a terrified Hitler, "I have great power! I can make you anything you want to be!"
"Put it in writing," Iron Jaw said, hovering closely over him, "I know now never to trust you! It's you I have to thank for making an iron jawed monster out of me, and I don't intend to ever let you forget it!"
Vonn Schmidts, also known as Iron Jaw, was assigned to the Gestapo and eventually became a field agent in the U.S. He was about as vicious and malignant an agent as the Gestapo ever created. Iron Jaw found that his most dangerous foe was not the F.B.I. but a very determined and non-powered young man called Crimebuster. From that meeting until 1954 Crimebuster pursued Iron Jaw to make him pay for the deaths of his parents. Twice Crimebuster thought that he had killed Iron Jaw and twice he failed.
"I have discovered the ancient art of suspended animation!" Iron Jaw explained later to Crimebuster. "Through tremendous inner control, I can virtually slow down my body to a condition of coma indistinguishable from death!"
In 1956 Iron Jaw appeared in New York City as a down-and-out American. Though he had a vicious temper he was not the killer that he used to be. He was just a plain crime boss, with few or no references to his Nazi past. The later Iron Jaw was mean but he had friends (of a sort) in the earstwhile small-time crook Sniffer and a band of bungling hoodlums called the Deadly Dozen who repeatedly made him the butt of their jokes and hair-brained schemes (whether intentionally or not); folded into Sniffer's strip, he became a comedic caricature of his former self. In Boy Comics #99 he even got a new jaw. Only his name stayed the same.
With thanks to Geoffrey Tolle for much of the above. Additional text as related by Crimebuster from the story "The Death Chase".
Golden Age Greats #5: Iron Jaw vs. Crimebuster from AC Comics.