After joining Theon and Aeron in the harrying of the Stepstones, Dagmer gets convinced to join Theon's plan to take over Winterfell. He attacks Torrhen's Square to divert Rodrik Cassel's attention away from the city. After getting defeated by Rodrik, Dagmer retreats with his men while Theon captures Winterfell. He later returns when Rodrik leaves to tackle Theon.