On 5 March 1454, he married Elizabeth of Brandenburg, the widow of the Duke Joachim II "the Younger" of Pomerania-Stettin and daughter of Margrave John of the Neumark.

In 1458, Wartislaw's father died and he and his older brother, Eric II began jointly ruling Pomerania.

The key points were that the Dukes in Wolgast were allowed to keep Pomerania-Stettin, but had to accept that they were vassals of Brandenburg and held Pomerania as a fief.

After Wartislaw's death, Bogislaw X reunited all part of Pomerania and ruled the Duchy for almost fifty years.

The issue was finally settled by Bogislaw's sons George I and Barnim XI in the Treaty of Grimnitz of 1529.