At the beginning of his reign in the small principality, he managed to survive the invasion of the considerable forces of King Ottokar II of Bohemia, who was bounded to a Crusade against Lithuania.
Was probably at this point that Ziemomysł established close contacts with the Teutonic Order and Sambor II, Duke of Pomerelia, alliances which soon brought to him serious troubles - the revolt of his own subjects.
This preference to foreigners disliked the local knighthood,[2] and caused an armed conflict led by the bishop of Kujawy, Wolimir, in 1269.
Only through rapid action did Ziemomysł and the grant to further privileges to Bishop Wolimir allowed him to regain temporary control of his lands.
The complete normalization of Ziemomysł's rule took place two years later at the Congress of Rzepka, where after an agreement with Mestwin II, was stipulated that after his death the castellany of Wyszogród had to return to Inowrocław.