Christian I of Denmark was a king who ruled from 1448 to 1481. He was the first monarch of the House of Oldenburg and played a significant role in the unification of Denmark, Norway, and Sweden under the Kalmar Union. His reign marked a period of relative stability and growth for the region. Born in 1426, Christian I was the son of Count Gerhard VI of Holstein. He married Dorothea of Brandenburg, which strengthened his political alliances. Christian I's legacy includes the establishment of the Danish National Church and efforts to improve trade and commerce in his kingdom.