King Frederick I of Sweden reigned from 1720 to 1751. He was born on October 17, 1676, in the Duchy of Holstein-Gottorp. Frederick became king after the death of Charles XII, and his rule marked a shift towards a more parliamentary system, reducing the power of the monarchy in favor of the Swedish Riksdag (parliament). Frederick I was known for his interest in culture and the arts, promoting the development of Swedish architecture and music. He married Princess Ulrika Eleonora, who was the sister of his predecessor, and together they had several children. His reign is often seen as a time of relative peace and stability in Sweden.