Even the last loyal supporters who still regard Frederick II of Prussia as 'the Great' remain silent in shame when it comes to the conquest of Silesia. Here, the king clearly acted unjustly. This is not changed by his later heroic assertions during the Silesian Wars. Although he invoked legal grounds and had opinions drafted and published to justify his actions, these are dismissed today as overly forced and unconvincing. What specific legal grounds are involved? For centuries, Silesia was a contested territory among Poland, Hungary, and Bohemia. The Piasts—Polish kings and later Silesian dukes—navigated this landscape and ultimately aligned themselves with Bohemia. They became vassals of the Luxembourg king John of Bohemia, adhering to the rules of feudal law.