In 1409, during the Polish–Lithuanian–Teutonic War, Bogislaw VIII again allied with the Teutonic Order. He switched sides the following year and allied with Poland in 1410. He fought on their side during the Battle of Grunwald. On 29 August 1410, he pledged the submission of his duchies to the king of Poland. In the exchange, he received Lauenburg and Bütow Land as well as Człuchów, Biały Bór, Debrzno, Świdwin and Czarne. Bogislaw VIII died on 11 February 1418.