Margaret I (Danish: Margrete Valdemarsdatter; March 1353 – 28 October 1412) was Queen regnant of Denmark, Norway, and Sweden (which included Finland) from the late 1380s until her death, and the founder of the Kalmar Union that joined the Scandinavian kingdoms together for over a century.

She was a practical, patient administrator and diplomat,[15] albeit one of high aspirations and a strong will, who intended to unite Scandinavia forever into one single entity with the strength to resist and compete against the might of the Hanseatic League.

[25] Per contemporary sources, the marriage contract contained an agreement to give Helsingborg Castle back to Denmark, but that was not enough for Valdemar, who in June 1359 took a large army across Øresund and soon occupied Scania.

[25] King Magnus and the Hanseatic League could not disregard this provocation, and a trade embargo against Denmark was immediately enacted, with agreement about necessary military action.

[26] A storm, however, diverted her to the Danish island Bornholm, where the archbishop of Lund declared the wedding a violation of church law because Haakon had already been engaged to Margaret.

[29] Merete Ulvsdatter was a distinguished noblewoman and daughter of Bridget of Sweden, as well as the wife of Knut Algotsson, who was one of King Magnus's faithful followers.

Olaf died suddenly in 1387, aged 16, and Margaret, who had ruled both kingdoms in his name, was chosen Regent of Norway and Denmark in the following year.

Margaret, free from fear of domestic sedition, could now give her undivided attention to Sweden, where mutinous nobles, led by Birger (son of Bridget and brother of Martha),[7] were already in arms against their unpopular King Albert.

Fear of Margaret induced both the Mecklenburg princes and the Wendish towns to hasten to its assistance; and the Baltic and the North Sea speedily swarmed with the privateers of the Victual Brothers.

Albert failed to pay his ransom within the stipulated time, and the Hansa surrendered Stockholm to Margaret in September 1398 in exchange for commercial privileges.

[35] In 1389 she proclaimed her great-nephew, Bogislav, who changed his name to Erik of Pomerania (grandson of Henry of Mecklenburg), king of Norway, having adopted him and his sister Catherine.

On 20 July, Margaret capitalized on the general rejoicing by publishing the famous Treaty of Kalmar, "a masterly document that sealed the union of Norway, Sweden and Denmark".

[7] A few years after the Kalmar Union, the 18-year-old Erik was declared of age and homage was rendered to him in all his three kingdoms, although Margaret was the effective ruler of Scandinavia throughout her lifetime.

The offices of High Constable and Earl Marshal were left vacant; the Danehof fell into ruin, and "the great Queen, an ideal despot",[39] ruled through her court officials, who served as a superior kind of clerk.

In 1396, according to Grethe Jacobsen, she issued an ordinance that one should to a higher degree than hitherto respect and enforce peace towards church (pax dei), houses, farms, legal assemblies, workers in the fields – and women, expressed in the word "kvindefred".

Jacobsen believes that as punishment for rape was normally not associated with the other forms for upholding peace in the tradition of pax dei, this may be an expression of Margrete's perception of women as being particularly vulnerable in times of unrest, and for her own interpretation of the ruler as protector of personae miserabiles, which included maidens and widows.

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.

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.

[6] In contrast with the foreign policy of her venturesome father, Margaret's was circumspect and unswervingly neutral in the bloody war between France and England as well as other European conflicts.

[42] 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.

However, although there was no double wedding, Erik married the 13-year-old Philippa, daughter of Henry IV of England and Mary de Bohun, at Lund on 26 October 1406, sealing a purely defensive alliance.

Margaret 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.

This special, double-gendered title bestowed upon the holder the power and authority of a man (lord), of a woman (sovereign lady) and of the gender-neutral guardian.

)[53] When she married Haakon VI of Norway in 1363, he was co-King of Sweden, making Margaret queen consort, and despite being deposed, they never relinquished the title.

From 24 February 1389[1] to 28 October 1412, she was Queen of Denmark, Norway and Sweden and founder of the Kalmar Union, which united the Scandinavian countries for over a century.

[56] In Sweden, such a republican (opposed to monarchy) as Vilhelm Moberg lauded Margaret as adverse to warfare and called her the greatest monarch the Nordic countries ever had.

[57] Professor Kjell Kumlien [de; sv] wrote in 1949: She made reality of political plans and aspirations which had previously been tried without nearly as much success by both Swedish and Danish kings.

The reason why she succeeded must be sought in no small part in her own eminent political talent, distinguished by strength and endurance as well as flexible and winning negotiating skill.

In an uncanny way, her person and deeds are united in the deeply felt communality of the Nordic kingdoms ...[58]In The Middle Ages: Dictionary of World Biography, Volume 2, McFadden opines that "Margaret's achievement at a time when all Scandinavia was being threatened by German cultural and economic domination was to unite the kingdoms and not only hold back the Germans but also regain lands lost to the south.

At the time of her death, the Scandinavian Union was by far the most powerful force in the Baltic; it was also the second largest accumulation of European territory under a single sovereign.