In the early 1170s, a Danish army under King Valdemar I besieged Szczecin Castle.
Reportedly, Wartislaw II surrendered and handed the castle to the Danes.
The fact that he was their guardian is considered a strong indication that he was closely related to them; the exact family relationship is unknown.
Wartislaw II was charged with convincing King Canute VI of Denmark to enfeoffed the young Dukes with Pomerania.
However, a revolt against Denmark broke out during his rule, and in 1189, Canute VI deposed him and appointed Prince Jaromar I of Rügen as regent.