Books like Vinland Saga, Volume 11: The Mighty Laid Low

The Mighty Laid Low Thanks to his claim by lineage, the attackers surrounding Jomsborg want Thorfinn to be their leader, but it is a mantle he intensely rejects. When the battle for leadership over the powerful Jomsvikings reaches a stalemate, Thorfinn must make a critical decision. With Gudrid held captive within the fortressed city, walking away will not be an option. He must infiltrate Jomsborg to break her out, and the ensuing battle will leave the greatest mercenary force in the North Sea changed forever…