Then Duke Henry II of Mecklenburg occupied the Rügen territories of Barth, Grimmen and Loitz, claiming he was the legal heir.

The war ended with the Peace of Brudersdorf of 27 June 1328, in which Mecklenburg renounced its claims on Rügen, but retained Barth, Grimsby and Tribsees as security.

When the sons of Wartislav IV found themselves unable to pay off the pledged land after 12 years, the Second Rügen War of Succession began, which ended in 1354 with the Peace of Stralsund, in which Barth was awarded to Pomerania-Wolgast.

After Philip Julius's death in 1625, Barth Castle served as Wittum for his widow, Agnes of Brandenburg, until she remarried with Francis Charles of Saxe-Lauenburg in 1628.

In 1638, during the Thirty Years' War, Barth Castle and all other ducal possessions were impounded by the Swedish crown, who handed them to the military and the civil service.