According to Thomas Kingston Derry, Margrethe tried to provide the union with a sound economic basis. In the process, each of her measures (recovery of crown lands from nobility and the church, new taxes and new coins) hurt the interests of powerful classes, but she prevented them from having leadership by making little use of separate councils of her three kingdoms, relying on a body of civil and ecclesiastical officials she chose with great skills instead.
She placed Danes in Swedish and Norwegian bishoprics, while royal estates and castles were managed by castellans and bailiffs of foreign extraction. While this has been criticized as promoting Danes at the expense of Swedish and Norwegian people, Derry opines that considering she employed more Germans in her native Denmark than elsewhere, she was mainly interested in securing a loyal and efficient administration.
She travelled much, in her later years is said to have spent more time in Sweden than in Denmark. She encouraged intermarriages among the nobility of three realms. Her piety is well-known, and she gave strong backing to the canonisation of St.Brigitta, helped to make Vadstena into a strong cultural centre and encouraged the spread of “Brigittine language”, which led to many Swedish expressions coming into use among Danes and Norwegians.
In contrast with the foreign policy of her venturesome father, Margrethe’s was circumspect and unswervingly neutral in the bloody war between France and England as well as other European conflicts. However, she spared no pains to recover lost Danish territory. She purchased the island of Gotland from its actual possessors, Albert of Mecklenburg and the Livonian Order, and the greater part of Schleswig was regained in the same way.
In 1402 Margrethe entered into negotiations with King Henry IV of England about the possibility of a double-wedding alliance between England and the Nordic Union. The proposal was for King Eric VII-III-XIII of Denmark, Norway and Sweden to marry Henry’s daughter Philippa, and for Henry’s son, the Prince of Wales and future Henry V of England, to marry Eric’s sister Catherine.
According to Marc Shell, Margrethe’s vision was that one day, two unions would unite to recreate Canute the Great’s Empire of the North. The English side wanted these weddings to seal an offensive alliance that could have led the Nordic kingdoms to become involved in the Hundred Years’ War against France.
Margrethe followed a consistent policy of not becoming involved in binding alliances and foreign wars, and therefore rejected the English proposals. However, although there was no double wedding, Eric married the 13-year-old Philippa, daughter of Henry IV of England and Mary de Bohun, at Lund on October 26, 1406, sealing a purely defensive alliance. For Eric’s sister Catherine, a wedding was arranged with Johann, Count Palatine of Neumarkt. Margaret thus acquired a South German ally, who could be useful as a counterweight to the North German Princes and cities.
In 1412, Margrethe tried to recover Schleswig, and thus entered a war with Holstein. Before that she had managed the recovery of Finland and Gotland. While winning the war, Margrethe died suddenly on board her ship in Flensburg Harbor.
In October 1412, she set sail from Seeland in her ship. She attended several debates, which reportedly had brought matters to a state of promising forwardness. On retiring to her vessel though, with the intention of leaving the port, “she was seized with sudden and violent illness.”
Margrethe apparently foresaw the end of her life, as she ordered thirty seven marks to be paid to the nearby monastery of Campen for a perpetual mass for her soul. Beyond this, there is no discussion in the historical record regarding her demise.
She died on the night of October 28, 1412, the vigil of St. Simon and St. Jude. Possible scenarios that have been suggested include plague, shock from the death of Abraham Brodersson (whom 18th century authors have alleged was the father of a daughter Margrethe had, while 19th century authors have blamed the story on a mistranslation), or poisoning by King Eric.
Her sarcophagus, made by the Lübeck sculptor Johannes Junge in 1423, is situated behind the high altar in the Roskilde Cathedral, near Copenhagen. She had left property to the cathedral on the condition that Masses for her soul would be said regularly in the future. This was discontinued in 1536 during the Protestant Reformation, though a special bell is still rung twice daily in commemoration.