Complex sentence: King Erik II other war expeditions together with the Outlaws, and probably also his brother Duke Haakon, came to Aalborg in 1290, and they were there for 15 days in the hope that citizens would help and support him.
Split into simpler sentences: King Erik II undertook other war expeditionswith the Outlaws, and probably also with his brother Duke Haakon. He arrived in Aalborg in 1290, and was there for 15 days in the hope that citizens would help and support him.