The Kalmar Union was established under the rule of Margaret I of Denmark, effectively bringing together the three Nordic kingdoms of Denmark, Norway, and Sweden. The union was formally proclaimed during a ceremony in Kalmar, Sweden, which symbolized the merging of these three nations into a single political entity. Margaret I, who had served as regent for both Denmark and Norway, played a crucial role in initiating this union, as she sought to enhance her influence and protect her realms from external threats, particularly the expanding power of the Hanseatic League. The union aimed to unify the military and economic resources of the member kingdoms, thereby creating a stronger front against potential aggressors.The alliance was characterized by its aims of cooperation and mutual support, allowing for joint defense and combined efforts in trade. As part of this union, the three kingdoms would share a common monarch, and although they maintained their respective laws and customs, the union fostered a sense of shared identity among the Nordic peoples. The Kalmar Union would, however, face challenges in the following years due to internal conflicts and power struggles, which ultimately undermined its stability. Despite this, the union was a significant political development in medieval Scandinavia, influencing the region’s governance and affecting future relations among the Nordic states.