He allowed the Victual Brothers, a pirate organization assaulting vessels of the Hanseatic League in the Baltic Sea, to use the Peene river as a winter refuge and the Bay of Greifswald as a basis.

In 1398, he signed a treaty with the Teutonic Knights not to further support the Victual Brothers (then also "Likedeelers"), but kept on engaging in piracy himself.

To avoid this fate, he went on a pilgrimage to Kenz near Barth, but died on his way in Pütnitz (a part of today's Ribnitz-Damgarten) on 23 September 1405.

He was buried in Kenz, where a large wooden statue resembling Barnim was furnished.

[1] He married Veronica of Hohenzollern, daughter of Frederick V, Burgrave of Nuremberg, and had at least two sons: