During Valdemar I's reign, Denmark transformed into a significant power in the Baltic Sea region. He and his trusted advisor, Absalon, initiated the construction of a castle in the village of Havn, which would later evolve into Copenhagen, the modern capital of Denmark. Together, Valdemar and Absalon expanded Denmark's influence and secured a foothold on the southern shores of the Baltic Sea by subduing the Principality of Rügen in 1168. This marked the beginning of Denmark's territorial expansion in the Baltic, which would later bring it into competition with other powers such as the Hanseatic League, the counts of Holstein, and the Teutonic Knights.
Danish Empire and campaigns 1168-1227. @ Tinkaer1991
In the 1180s, Danish control extended further as they brought Mecklenburg and the Duchy of Pomerania under their influence. In these southern territories, the Danes promoted Christianity, establishing monasteries like Eldena Abbey and contributing to the broader process of German eastward expansion, known as the Ostsiedlung. Despite their early successes, Denmark lost most of these southern conquests after suffering a decisive defeat at the Battle of Bornhöved in 1227, although the Rugian principality remained part of Denmark until 1325.
In 1202, Valdemar II ascended to the throne and launched a series of campaigns, or "crusades," that expanded Denmark's influence further into the Baltic region, including the conquest of modern-day Estonia. This period marked the beginning of Danish Estonia. According to legend, during the Battle of Lindanise in 1219, the Danish flag, the Dannebrog, miraculously fell from the sky, becoming a symbol of the nation. Despite this legendary victory, Denmark faced several defeats in the following years, culminating in their loss at the Battle of Bornhöved in 1227. This defeat marked the end of Danish control over their North German territories, and Valdemar II was saved from capture only through the bravery of a German knight who carried him to safety.
Following these setbacks, Valdemar II shifted his focus to internal reforms. He introduced a feudal system, granting lands to nobles in exchange for service, which increased the power of the noble families (højadelen) and gave rise to a class of lesser nobles (lavadelen). This shift in power led to the erosion of the traditional rights enjoyed by free peasants since Viking times.
The waning power of the Danish monarchy, coupled with the growing strength of the nobility and conflicts with the Church, led to an extended period of tension, known as the "archiepiscopal conflicts." By the late 13th century, royal authority had diminished significantly, and the nobility forced the king to grant a charter, recognized as Denmark's first constitution. This period of weakened royal power opened opportunities for the Hanseatic League and the Counts of Holstein to gain influence, with the latter acquiring large portions of Denmark through fiefdoms granted by the king in exchange for financial support.
In his later years, Valdemar II devoted himself to compiling a comprehensive set of laws for Denmark. He developed legal codes for Jutland, Zealand, and Skåne, which remained in use until 1683. These codes marked a significant departure from the localized laws established by regional assemblies (landsting). The Code of Jutland (Jyske Lov) was approved by the nobility at a meeting in Vordingborg in 1241, shortly before Valdemar’s death. The code abolished outdated practices such as trial by ordeal and trial by combat, establishing a more structured legal system.
Valdemar II is remembered as a central figure in Danish history, often referred to as "the king of Dannebrog" and celebrated as a legislator. The period following his death saw civil wars and political fragmentation, making him appear to later generations as the last king of a golden era in Danish history.