Valdemar’s heirs brought the kingdom to its medieval apogee. His youngest and only surviving child, Margaret I (Margrethe I), had married a prince of Sweden, Haakon VI Magnusson, then king of Norway. Their son Olaf (Oluf) was chosen as king of Denmark in 1376. Margaret, as guardian and regent, followed a policy of peace abroad and strengthening the crown internally. In 1380, when Haakon died, Olaf, still a minor, was chosen as king of Norway as well. This brought not only Norway but also Iceland, the Faroe Islands, and Greenland under the Danish crown. Margaret also pushed Olaf’s claim to the Swedish throne, as he was last in the male line of Swedish kings. Before she could win the crown for him, however, Olaf died in 1387. Margaret was soon acknowledged as regent in Denmark and Norway, and rebellious Swedish nobles, dissatisfied with the rule of Albert of Mecklenburg, hailed her as regent in Sweden as well. War between the supporters of Margaret and Albert continued until 1398, when Albert’s forces finally surrendered Stockholm to Margaret.

Margaret’s rule was predicated on her control of the succession, and so she had adopted her great-nephew Erik of Pomerania. In 1397 at Kalmar, Swed., Margaret oversaw the coronation of Erik as king of Denmark, Norway, and Sweden—thus establishing the Kalmar Union of the three Scandinavian states. Although Erik, known as Erik VII in Danish history, was the titular king, Margaret retained actual power until her death in 1412.

The policies of Erik VII and the subsequent rulers of the Kalmar Union aimed to consolidate and hold together this rather disparate collection of territory. In 1434 a rebellion broke out in Sweden, and the spirit of revolt spread to the king’s enemies in Denmark and Norway. He was deposed in 1439 by the Danish and Swedish councils of the realm and in 1442 by Norway. The joint crown was offered to Erik’s nephew Christopher III, but his reign did little to strengthen the union, which was temporarily dissolved after his death in 1448. Christian I, founder of the Oldenburg dynasty, succeeded to the Danish and Norwegian thrones, but efforts to bring Sweden back into the union were only intermittently successful, and when Christian died in 1481, he did not rule that country. He was succeeded by his son John (Hans), whose coronation charter of 1483 acknowledged him as king of all three countries, but he actually held the Swedish throne only from 1497 to 1501.

Swedish revolts continued into the reign of Christian II, who succeeded his father, John, as king of Denmark and Norway in 1513. After defeating the army of the Swedish regent in 1520, Christian was crowned king of Sweden. Following his coronation, he executed more than 80 opponents of his regime in what became known as the Stockholm Bloodbath. Outrage over the massacre encouraged a final rebellion by the Swedes, who declared independence in 1523—marking a permanent end to the Kalmar Union. Opposition to the king grew in Denmark as well; the nobles of Jutland deposed him that year and drove him into exile. The Danish and Norwegian crowns then passed to Christian’s uncle, Frederick I.

Late medieval society

During the Late Middle Ages the Danish people became more sharply divided into social classes. The nobility in particular developed the characteristics of a caste. Prior to the 15th century any Dane could become a noble, provided he could render military services to the king at his own expense, particularly by providing a prescribed number of men-at-arms. In return, he was exempted from all taxes. From the 15th century, however, he had to show that his forefathers had enjoyed tax exemptions for at least three generations. In addition, the king sought to assume the right to issue titles of nobility. These measures helped to limit the number of nobles in the kingdom. During the 15th century the nobility comprised 264 families, but this number fell to 230 in 1500 and to 140 (including at most 3,000 persons) in 1650; the Gyldenstjerne and Rosenkrantz families (whose names are commemorated in William Shakespeare’s Hamlet) were among the most important.

Agriculture remained the principal industry. The cultivated land, apart from about 1,000 manors, consisted of about 80,000 farms, clustered together in groups of 5 to 20 as villages. These were managed by peasant farmers in common, whether they held their farms as freeholds or as copyholds. In 1500 about 12,000 peasants owned farms, about 18,000 were copyholding peasants on crown lands, and about 30,000 were copyhold tenants of lands belonging to the church or the nobles.

The peasantry suffered a decline during the Late Middle Ages. Such factors as the outbreak of plague in the mid-14th century, the expropriation of peasant lands, and the migration of young people from farms to towns led to a shortage of labor and a drop in agricultural production. A significant number of peasant farms and even whole villages were abandoned. The nobles—especially on Zealand, Funen (Fyn), and the smaller islands—responded to the crisis by establishing vornedskab, an institution that, like serfdom, tied peasant men and women to the estate of their birth.

Meanwhile, under the Kalmar Union, Danish towns prospered, and the influence of the burghers, or townspeople, grew. By 1500 there were approximately 80 towns, most of them fortified but all of them small; Copenhagen had at most 10,000 inhabitants. A monopoly on internal trade granted by King Erik VII improved the economic position of the burghers, and many German merchants took out citizenship in the towns in order to compete.