Frederick William, often referred to as the "Great Elector," was a significant ruler of the {Brandenburg-Prussia} region in the 17th century. He reigned from 1640 to 1688 and is known for his efforts to strengthen the state and modernize its military. His leadership helped lay the foundation for the future {Kingdom of Prussia}. He played a crucial role in the {Thirty Years' War}, which devastated much of Europe. Frederick William focused on rebuilding his territories, promoting religious tolerance, and encouraging economic development. His policies and reforms contributed to the rise of Prussia as a major European power.