Frederick William, known as the Great Elector, ruled the Duchy of Prussia from 1640 to 1688. He is recognized for his significant role in strengthening the Brandenburg-Prussia state during a time of political instability in Europe. His military reforms and diplomatic strategies helped expand his territory and influence, laying the groundwork for the future Kingdom of Prussia. The Great Elector was also a proponent of religious tolerance, allowing various faiths to coexist in his realm. His policies attracted immigrants, boosting the economy and population of Prussia. Frederick William's leadership set the stage for his descendants, including Frederick the Great, to further elevate the region's status in Europe.