Magnus IV was King of Sweden from 1319 to 1364, King of Norway as Magnus VII from 1319 to 1343, and ruler of Scania from 1332 to 1360. By adversaries he has been called Magnus Smek, referring to Magnus Eriksson as Magnus II is incorrect. The Swedish Royal Court lists three Swedish kings before him of the same name, Magnus was born in Norway in April or May 1316 to Eric, Duke of Södermanland and Ingeborg, a daughter of Haakon V of Norway. Magnus was elected king of Sweden on 8 July 1319, under the regencies of his grandmother, Helwig of Holstein, and his mother, Ingeborg of Norway, the countries were ruled by Knut Jonsson and Erling Vidkunsson. Magnus was declared to have come of age at 15 in 1331 and this provoked resistance in Norway, where a statute from 1302 stipulated that a king came of age at the age of 20, and a rising by Erling Vidkunsson and other Norwegian nobles ensued. In 1333, the rebels submitted to King Magnus, in 1332 the King of Denmark, Christopher II, died as a king without a country after he and his older brother and predecessor had pawned Denmark piece by piece. King Magnus took advantage of his neighbours distress, redeeming the pawn for the eastern Danish provinces for a amount of silver. On 21 July 1336 Magnus was crowned king of both Norway and Sweden in Stockholm and this caused further resentment in Norway, where the nobles and magnates desired a separate Norwegian coronation. A second rising by members of the nobility of Norway ensued in 1338. In 1335 he married Blanche of Namur, daughter of John I, Marquis of Namur, and Marie of Artois, the wedding took place in October or early November 1335, possibly at Bohus castle. As a wedding gift Blanche received the province of Tunsberg in Norway and they had two sons, Eric and Haakon, plus at least three daughters who died in infancy and were buried at Ås Abbey. Opposition to Magnus rule in Norway led to a settlement between the king and the Norwegian nobility at Varberg on 15 August 1343, in violation of the Norwegian laws on royal inheritance, Magnus younger son Haakon would become king of Norway, with Magnus as regent during his minority. Later the same year, it was declared that Magnus older son, thus, the union between Norway and Sweden would be severed. This occurred when Haakon came of age in 1355, on 12 August 1323, Magnus concluded the first treaty between Sweden and Novgorod at Nöteborg where Lake Ladoga empties into the Neva River. The treaty delineated spheres of influence among the Finns and Karelians and was supposed to be an eternal peace, but Magnus relations with Russia were not so peaceful. In 1337, religious strife between Orthodox Karelians and the Swedes led to a Swedish attack on the town of Korela and Viborg, a Swedish commander named Sten also captured the fortress at Orekhov. In this treaty, the Swedes claimed that Sten and others acted on their own without the consent of the king, in 1335, Magnus outlawed Thralldom for thralls born by Christian parents in Västergötland and Värend, being the last parts of Sweden where slavery had remained legal. The Novgorodians retook the fortress in 1349 after a seven-month siege, while he spent much of 1351 trying to drum up support for further crusading action among the German cities in the Baltic States, he never returned to attack Novgorod
Magnus on the title page of his Swedish national lawcode, c. 1350.
Historic map of when Sweden was divided between Magnus Eriksson and Erik Magnusson during 1357
King Magnus's shipwreck from a Russian manuscript
Head from Trondheim thought by Professor Jan Svanberg to be King Magnus.