The Lublin Agreement was a treaty signed on July 1, 1569, between the Kingdom of Poland and the Grand Duchy of Lithuania. This agreement aimed to create a closer political union between the two states, leading to the formation of the Polish-Lithuanian Commonwealth. The union allowed for shared governance while maintaining separate laws and administrations for each entity. The agreement was significant in European history as it strengthened the power of the Commonwealth, making it one of the largest and most influential states in Europe at the time. The Lublin Agreement also established a common parliament and military, fostering cooperation between the two nations.