Under mysterious events during the middle 1940s to the year 1950, several superheroes and their young sidekicks disappeared from their native Earth-Two, and later became the first wave of costumed crusaders of Earth-One.
From in story reverences, we know that: a.) there was a connection between Hank "Commander Steel" Heywood... originally of Earth-Two and the first All-Star to migrate to Earth-One... and Per Degaton, the time travelling tyrant, b.) several heroes' "DC’s Who's Who" entries state both their affiliation to Earth-Two's All-Star Squadron and events as well as people in their lives on Earth-One, c.) Steel's propensity with recruiting Infinity, Inc. to solicit assistance from Earth-Two heroes on what he viewed as hero deprived Earth-One. Connecting the dots provides us with an idea as to the order of events that precipitated the migration of a dozen mystery men and their allies during 1946 from Earth-Two to Earth-One, as follows....
Steel had in his possession a futuristic transponder that a German scientist purchased from the Monitor in order to send the Justice Battalion into hyperspace. When he accidentally was shunted to Earth-One by this device in 1942, Heywood joined the military and then returned to the United States towards the end up World War II, Hank used this device to contact anyone from his home world in 1945/46.
Mekanique had herself betrayed the Squadron in 1942, and although her body had been destroyed her head with its time-space crystal was preserved at Project M by the lab assistant known as Per Degaton, who was a colleague of Chuck Grayson. Thus, prior to starting his criminal career, Degaton formed a relationship through Robotman with Heywood.
Heywood was able through Monitor's transponder and the robot Mekanique to contact her former partner and Steel’s old ally Robotman aka Paul Dennis. Utilizing her ability to cross dimensional planes, Robotman initiated Mekanique's trans-dimensional capabilities and brought along with himself several fellow All-Stars to Earth-One. Robotman and Steel recruited TNT, Dyna-Mite, Manhunter, Guardian among with Newsboy Legion and his younger brother Will, Air Wave, and Zatara. Years later, as mentioned earlier, Steel would do much the same thing when he temporarily recruited Infinity, Inc. of Earth—Two to battle the newest incarnation of the Justice League on Earth-One.
No doubt these heroes and their colleagues were inspired by the example a few years prior of Uncle Sam, a patriotic hero like Steel who recruited several members of the All-Star Squadron into forming the Freedom Fighters, protecting another earth in Earth-X that had no superheroes. And so, the first generation of superheroes on Earth-One were migrants from Earth-Two.
Heywood would secretly sponsor research on cloning technology through his Council and the young adept minds of the Newsboy Legion who became aspiring geneticists using perfect physical specimens as Guardian and Manhunter, incorporating cybernetic technology Robotman utilized, while TNT and Dyna-Mite could add insight into atomic technology. Larry Jordan incorporated the Monitor's device into teleportation technology he would use as Air Wave. All of these great minds were orchestrated by Heywood In order to bring about a new world order on their adopted world.
- Air Wave and Zatara sired their counterparts in a son and daughter respectively, with Air Wave perishing in the prime of his life and Zatara journeying throughout the Multiverse before reunited with Zatanna
- The Guardian aka Jim Harper and his little brother Will pursued civilian lives as had the four Newsboy Legionnaires. Eventually, Jim and the Newsboys were each cloned for a new generation, while Will perished shortly after having a son of his own in Roy "Speedy" Harper, counterpart to his native world's Speedy!
- Paul Kirk retired his Manhunter alter ego, and during a big game hunt ended up in a coma for decades. When he awoke, he learned he had become the template for an army of clones of the Council. This Council attempted to rule the world, which Kirk would help defeat at the cost of his life, just as his surviving clone would do when facing Darkseid.
- TNT and Dyna-Mite had been brought in during the waning days of the Manhattan Project only to find that their powers had increased and become unstable on their adopted world. They were kept in an underground bunker when their powers got out of control and ultimately moved to the cities of Kandor and Atlantis to live out their lives after meeting Earth-One's Super Friends. TNT joined the Kandorians on the new transdimensional world of Rokyn while Dyna-Mite remained in Aquaman's city indefinitely.
- Robotman made several appearances on Earth-One from 1946 until 1953, then worked alongside the Justice League of America during their first case. Robotman shortly thereafter was shifted back to Earth-Two during an cosmic event involving the Anti-Matter Man. Back home, Robbie resumed his crusade until he was trapped in suspended animation within a cave for two decades, and later had his mind transplanted into the body of his now brain dead former colleague Chuck Grayson.
- In 1950, Sargon had himself traveled from Earth-Two to Earth-One and become reacquainted with these heroes and Hank Heywood. He left his native Earth at that time due to all superheroes (aside from a select few) being banned by the government at that time.
Decades later, Steel employed Degaton and charged him with the task of rebuilding Mekanique’s body after his initial plans with his fellow All-Stars had failed given their own life choices. During this occasion, Degaton retrieved Mekanique's head, attaching it to a new body and sent her to Earth-One to fulfill her mission before she returned to his side in a post-Crisis universe.