 This led James' father Jan III Sobieski to put a plan together to seize power in Ducal Prussia and elevate his son.The secret treaty of Jaworów signed in 1675 between the Polish king and France committed Poland to aiding France against Brandenburg-Prussia in exchange for French monetary subsidies and support for Polish claims over Ducal Prussia.The French promised to mediate between Poland and the Ottoman Empire so that Polish forces could be diverted from the southern border.