Emil Sledgeski was born in Poland and immigrate to the US in the 1910’s with his family, settling in Chicago.  Sledgeski was born a unique anatomic specimen, notably his enormous hands that weighted about ten pounds each.  Starting school in a poor neighborhood, Sledgeski quickly became the target of bullies who labeled him a freak and pushed him around.  While his English was poor, his understanding of violence was extremely clear and using his abnormally sized fists, he quickly made a name for himself as someone not to be trifled with.  He was befriended by another boy, Edward Runyon, from the same neighborhood, who nicknamed him “Sledgehammer”, a name that stuck with him for the rest of his life.  Some years later with both boys were teens, Sledgeski was involved in an altercation that resulted in someone’s death.  Runyon hid him until he was eventually arrested as a police tip and sentenced to prison for manslaughter in ~1924.

Fifteen years later, the military adventurer Steel was contacted by Runyon for a secretive meeting in downtown Manhattan.  Arriving, he saw cars of thugs menacing Runyon and quickly intervened.  As Steel gained the upper hand, the massive figure of Sledgehammer emerged from a car and engaged Steel, eventually slamming him into it bus where he became wedged in the side.  The sounds of sirens heralded the arrival of police and lacking his Chicago connections to get him off the hook, Sledgehammer fled before finishing off Steel. 

After Steel was extracted from the bus, Runyon took him to his apartment and shared the history he had with Sledgeski.  While they had been friends as youths, Sledgehammer had become a mob boss while Runyon had moved to New York and become a newspaper magnate.  He claimed that the gangster had an unknown vendetta and he needed Steel to thwart Sledgehammer’s intentions and save Runyon’s life. Steel agreed to engage Sledgehammer at a seedy hotel but insisted on Runyon’s accompaniment.  Despite the newspaperman’s protests, Steel drug Runyon along and after sedated the guards, burst into Sledgehammer’s room while the gang lord had dinner.  The two engaged in a furious battle of violent fists which ended in Steel tricking Sledgehammer into running himself into a wall, knock himself out and becoming stuck in the structure itself.   As the police arrived to take Sledgeski to jail, Steel confronted Runyon and revealed his knowledge of Sledgeski’s vendetta – that is was Runyon who had turned in friend for the police reward, allow himself to escape the poverty of Chicago and locking Sledgeski into a life of crime.   Steel left the newspaperman wondering if Sledgehammer’s life would have been different if he had not been betrayed by his friend.

The subsequent activities and ultimate fate of Sledgehammer on Earth-Two are not recorded.