The Kingdom of Poland and the Grand Duchy of Lithuania defeated the Teutonic Knights at the Battle of Grunwald, the decisive engagement of the Polish–Lithuanian–Teutonic War.

The Crown of the Kingdom of Poland was a political and legal concept formed in the 14th century in the Kingdom of Poland, assuming unity, indivisibility and continuity of the state. Under this idea, the state was no longer seen as the patrimonial property of the monarch or dynasty, but became a common good of the political community of the kingdom. This notion allowed the state to maintain stability even during periods of interregnum and paved the way for a unique political system in Poland, characterised by a nobles-based parliament and the free election of the monarch. Additionally, the concept of the Crown extended beyond existing borders, asserting that previously lost territories still rightfully belonged to it. The term Crown of the Kingdom of Poland also referred to all the lands under the rule of the Polish king. This meaning became especially significant after the union with the Grand Duchy of Lithuania, when it began to be commonly used to denote the Polish part of the joint Polish-Lithuanian Commonwealth.