How did Thor entered the MARVEL universe?

11th Century

Around 1000 A.D., Vikings landed on parts of North America and declared it for Odin and the Asgardian gods whom they worshipped

Odin caused Thor to live on Earth in the mortal guises of the Germanic heroes Siegmund and his son, Siegfried. In these two roles, Thor played a major role in Odin's efforts to regain the dangerously powerful Ring of the Nibelung. 

13th Century

In 1248 A.D., a group of Vikings were exiled from Norway and traveled west along the Atlantic. They eventually settled on an uncharted island where they lived in seclusion for many centuries until the 20th Century.^[22]

Legacy

During World War II; Adolf Hitler succeeded in contacting Thor and deceived him into aiding the cause of the Germans, the descendants of the people who had once worshiped him, in the current war.

Thor therefore clashed with the Invaders and nearly killed the second Union Jack with a blast of lightning from his enchanted hammer. Learning that Hitler was evil, Thor vowed to aid him no more, and withdrew most of the electricity in Union Jack's body back into his hammer, somehow restoring him to health in the process. The second Union Jack now possessed the superhuman power to discharge electrical bolts from his body.^[23]

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