The
Polish–Lithuanian Commonwealth, or
Republic of Both Nations, formally the
Kingdom of Poland and the Grand Duchy of Lithuania, after 1791 the
Commonwealth of Poland, was a dualistic
state, a bi-
confederation, of
Poland and
Lithuania ruled by a common monarch, who was both the
king of Poland and the
grand duke of Lithuania. It was one of the largest and most populous countries of 16th- and 17th-century Europe. At its peak in the early 17th century, the Commonwealth spanned some and sustained a multi-ethnic population of 11 million. The union was formalized by the
Union of Lublin in July 1569, but the
Crown of the Kingdom of Poland and the
Grand Duchy of Lithuania were in a de-facto
personal union since 1386 with the marriage of the Polish female king (as she was crowned as actual ruler)
Jadwiga of Poland and Lithuania's Grand Duke
Jogaila, who was crowned King
jure uxoris Wladyslaw II Jagiello of Poland. The
First Partition of Poland in 1772 and the
Second Partition of Poland in 1793 greatly reduced the nation's size and the Commonwealth disappeared as an independent state following the
Third Partition of Poland in 1795.