Vikings: Every Character Based On Real Historical Figures

Charles II the Bald was the king of West Frankia when Ragnar Lothbrok was said to have laid siege to Paris in 845 AD. During that attack and later ones Charles paid off the Vikings when they seemed to have the upper hand, sending them home with the gold they wanted while avoiding further attacks.

Although the show is correcting in showing Ragnar fighting Charles the Bald, Rollo did not interact with him. In the show, Charles the Bald is the one who gives Rollo the Duchy of Normandy, but Rollo would not have been fighting in Paris until after his death.

Although Charles is named the emperor during Ragnar's attack in the show, he didn't get the title until 875 AD in real life.