Frederick III of Denmark was a king who reigned from 1648 until his death in 1670. He was born on March 18, 1609, and was a member of the House of Oldenburg. His reign is noted for the establishment of absolute monarchy in Denmark, which significantly increased the power of the crown over the nobility and the government. Frederick III is also known for his efforts to strengthen the Danish military and improve the economy. He was married to Sophia Amalie of Brunswick-Lüneburg, and they had several children, including Christian V, who succeeded him as king.