Charles, the Swedish Duke of Sodermanland (later to become King Charles XIII of Sweden) spent a good deal of his adult life (prior to his ascension) studying the history of the Knights Templar. He traveled throughout Europe and established an extensive library on Templar history, Alchemy and so on. This library is now in the possession of the Order of Swedish Freemasons. The order of Freemasonry established by Charles (The Swedish System) continues to be practiced in Scandinavia.
References
Haagensen, E. & Lincoln, H. (2002) The Templars' Secret Island. The Knights, the Priest and the Treasure. New York: Barnes and Noble Books. ISBN 0-7607-3205-1
Charles' office of secretary of state and his care for the business of the family did not prevent him from giving time to study, and even to recreations in the form of playing the lute and violoncello, and a game of ball.
Charles was now assured that it was his duty to remain in the world; but all the more he felt he ought to visit his diocese, though the pope always opposed his departure.
Charles was at Lodi, at the funeral of the bishop.
CharlesXIII (Karl XIII) (October 7, 1748 – 1818), was King of Sweden from 1809 and King of Norway (where he was known as Charles II) from 1814 until his death.
On the death of Gustav III, Charles, now duke of Sudermannia, acted as regent of Sweden till 1796; but the real ruler of the country was the narrow-minded and vindictive Gustaf Adolf Reuterholm, whose mischievous influence over him was supreme.
These four years were perhaps the most miserable and degrading in Swedish history (an age of lead succeeding an age of gold, as it has well been called) and may be briefly described as alternations of fantastic jacobinism and ruthless despotism.