Hello!
Vinland Saga is a Japanese historical manga series written and illustrated by Makoto Yukimura.
Ref: https://booksandbao.com/why-the-vinland-saga-manga-is-a-masterpiece/
In 1013 AD, the young Thorfinn works for Askeladd in the hopes of challenging to a duel and kill him in revenge for his father's death in 1002 AD when they were attacked by him on a journey to England. Askeladd's company found employment in 1013 AD as mercenaries under the Danish King Sweyn in the Danish invasion of London by the British and Thorkell the Tall, Thorfinn's fight-loving uncle who served with Thors in the Jomsvikings.
When Thorkel takes Sweyn's son Prince Canute captive, Askeladd's company capture the prince with the intent of selling him to either side for a profit. Askeladd changes his plan to act on his personal agenda as a descendant of Artorius to secure his mother's homeland of Wales from being invaded.
While Askeladd succeeds in making Canute assertive, he learned that Sweyn intended for his son to die so that his oldest son Harald would succeed him and prevent a schism among the Danes. Askeladd is ultimately forced to sacrifice himself by killing Sweyn during an audience when the king announces his plan to invade Wales, feigning madness as Canute kills him, so the prince could take over Dane-occupied England without question. But Thorfinn scars Canute in an attempt on the prince's life and is sentenced by an empathic Canute with life in enslavement.
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