King of Norway and Sweden. In Sweden he was Magnus IV. Of the Swedish Bielbo Dynasty, he was the grandson of Magnus III through Duke Eric, who had been murdered at the instigation of Magnus's exiled uncle, Ex-King Birger, in 1318. By 1319, his mother, Duchess Ingiburga, a Norwegian princess, had in fact become reigning Queen Mother and now had her 3 year old son elected King by the Swedish grandees that exercised such rights whenever the throne came up vacant. Magnus began his 45 year reign, the longest ever in Sweden, at first under his mother's regency, and when she had remarried and been removed, under a cabinet of other regents. Till 1355, because his mother was the daughter of the last and late Sverrir Dynasty king, Magnus also reigned in Norway, then including Iceland. Thus he filled the thrones of both his grandfathers, and this was the first such formal union either nation ever had with another kingdom. He took over the reins of government himself in 1331, and four years later married a Belgian countess of noted beauty, Blanche, whom he had met on a journey to Flanders in 1334. King Magnus was considered a great legislator, enacting laws of the land that freed the slaves, arranging county and city administration, and defining the ruler's rights in what could be seen as a first body of constitutional law. The royal couple on horseback had nearly constant tours of their sizeable realm, which also included Finland, to judge all kinds of legal trials. He led a campaign in Estonia and gave Sweden her natural boundary, the seacoast in the south, by gaining the provinces of Scania and Hallandia from Denmark. 30 years later he lost not only Scania to the Danish king, but also the big Gothland isle. He and Queen Blanche, also often each in one of their two countries, ran a double kingdom plagued not only by the Black Plague, but also by poor finances and envious, often hostile noblemen. The royal couple's opposition to strong church influence in government affairs soon had them in trouble: A relative who had been one of the ladies of the queen's court, but now had moved to Rome and was known as Bridget the Holy, did severe and nearly everlasting damage to the reputations of both the king and queen. Magnus was accused of erotic deviations, at worst, both of extravagance, and Blanche of various murderous plots. The King's reign eventually had to be shared with each of his two sons. Deposed in Sweden in 1374 and imprisoned for three years by his nephew Albert, Magnus was released to join his younger son, Hacon VI of Norway. He continued to play a part there, still formally King of Iceland, until his drowning death in a shipwreck in the Bømla Fiord at age 58. His burial can be safely assumed to have taken place at St. Mary's in Oslo, now long in ruins, according Prof. Oscar Albert Johnson.