He fought in the Battle of Grunwald (July 15, 1410), where he defended Radzyń against the Teutonic Order. Later he played a prominent role in the civil wars in Bohemia during the reign of Wenceslas IV. In the Battle of Kutná Hora (1421) he defeated the army of the Holy Roman Empire and the Hungarian Kingdom. The effectiveness of his field artillery against the royal cavalry in this battle made it a successful element of Hussite armies.