The King of Norway by Cecelia Holland
My rating: 5 out of 5
The titular character is an Conn Corbannson, a hirdman to King Sweyn of Denmark, who is upset with his Danish leader because he won’t attack England. Sweyn however wants to teach Haakon the Jarl—the real King of Norway—a lesson and has asked for help from the Jomsvikings to help. During the welcome feast, Conn gets too drunk and swears to become ‘King of Norway’. It’s a vow Conn continually regrets, especially when he comes face-to-face with Haakon.