Treaty of Lublin

The Treaty of Lublin, signed in 1569, was an agreement that united the Kingdom of Poland and the Grand Duchy of Lithuania into a single political entity called the Polish-Lithuanian Commonwealth. This agreement allowed both states to retain their own laws and institutions but shared a common monarch and coordinated foreign policy and military efforts. The treaty aimed to strengthen both regions against external threats, particularly from neighboring powers, and laid the foundation for a culturally diverse, cooperative state that lasted for over two centuries.