Iron Jaw was a Nazi agent and an arch-rival of Crimebuster. He was originally a German soldier known as "von Schmidt" who fought for his country on the Belgian front during World War I. He served alongside the young Adolf Hitler. The two plotted to kill their superior and make it look like an accident. Although it worked, the superior remained alive long enough to throw a grenade in the duo's direction. Hitler ran away, leaving Von Schmidt to take the blunt of the blast. The explosion incinerated his jaw. It was replaced with a steel trap like prosthetic, earning him the nickname "Iron Jaw."
When Hitler came to power, Iron Jaw blackmailed Hitler into giving him and his son the freedom to do anything they wanted without fear of persecution. For reasons that are not altogether clear, Iron Jaw became Hitler's top agent, working to advance Nazi interests in United States. Iron Jaw became known for brutal methods, ruthlessly killing anyone who gets in the way.
In 1942, Iron Jaw was ordered to stop Mr Chandler, an American reporter, from reporting on Nazi atrocities in France. At first, he tried to blackmail the journalist by threatening to kill his wife and son. When that didn't work, Iron Jaw tried to kill him. Upon discovering that Mr. Chandler wasn't dead and was currently in a hospital, he killed him during surgery.
Mr. Chandler's son, Chuck Chandler, swore revenge, assuming the mantle of Crimebuster. Knowing that Iron Jaw would come after his mother next, the youth headed to Paris. Although Crimebuster managed to stop the initial murder attempt, Iron Jaw got his way when he torpedoed to boat she and Crimebuster were were traveling on.
Iron Jaw and Crimebuster clashed again when the Nazi agent kidnapped a group of young socialites that were fundraising for the Red Cross. The confrontation ended with Iron Jaw's apparent death.
However, Iron Jaw survived, reappearing a few months later. He was surprised to discover that Crimebuster persuaded his son to switch sides. Unable to handle it, Iron Jaw murdered his progeny and went after Crimebuster with renewed vigor.
The two fought on several more occasions, and Crimebuster prevailed every time. He was presumed dead after every confrontation, only to turn up alive every time. Eventually, Hitler grew tired of Iron Jaw's failures and sent an agent known as the Rodent to terminate him. The two fought and seemingly killed each other.
Iron Jaw did not re-emerge until the early 1950s. Once again, he went after his arch-enemy. When his initial attempt to kill Crimebuster ended in failure, Iron Jaw escaped and went on a bloody rampage. While hiding from the law, he offered his services to Communist agents. His first outing as a Communist agent ended in his capture. The next few clashes followed the same pattern - Iron Jaw broke out of prison and went on a crime spree, only to be recaptured by Crimebuster.
That changed when the Deadly Dozen, a group of gangsters that was originally created to oppose Daredevil, decided to bust Iron Jaw out of prison in hopes that he would help them pull off their latest crime. Although initially viewing his associates with contempt, they wound up sticking together, and Iron Jaw's opinion of his allies gradually softened. The association also softened his attitude. He became less bloodthirsty and a lot less competent.
This was a reflection of the trends that swept through the entire comic industry at the time. The advent of the Comic Code helped to cement the Iron Jaw's depiction. He underwent a plastic surgery to replace his artificial jaw with a more natural-looking prosthetic.
Iron Jaw continued working with the Deadly Dozen until Lev Gleason Publications went out of business.
He, like so many other characters from the 40's with no publishers was brought back by AC in the 80's.