Charles August was Crown Prince of Sweden briefly in 1810. Earlier, he had been the Danish viceroy of Norway. His name until 1810 was Prince Christian August of Augustenborg. Augustenborg Castle Duke of Augustenborg was a title conferred by the King of Denmark to the head of a certain younger branch of the House of Oldenburg (Danish, Oldenborg), the branch known in Danish as Slesvig-Holsten-Sønderborg-Augustenborg, and in German as Schleswig-Holstein-Sonderburg-Augustenburg. ...

On June 6, 1809 the duke regent of Sweden was proclaimed king, after Gustav IV Adolf was deposed. The new king Charles XIII accepted the new liberal constitution, which was ratified by the Riksdag of the Estates the same day. The new king was, at best, a useful stopgap, in no way likely to interfere with the liberal revolution which had placed him on the throne. Peace was what the exhausted nation now required. June 6 is the 157th day of the year in the Gregorian calendar (158th in leap years), with 1 day remaining // 1508 - Maximilian I, Holy Roman Emperor, is defeated in Friulia by Venetian forces; he is forced to sign a three-year truce and cede several territories to Venice 1513... Year 1809 (MDCCCIX) was a common year starting on Sunday (link will display the full calendar). ... Charles XIII (Swe: Karl XIII) (October 7, 1748 - February 5, 1818), was King of Sweden from 1809 and King of Norway (where he was known as Carl II) from 1814 until his death. ... The Riksdag of the Estates, or Ståndsriksdagen, was the name used for the Estates of the Swedish realm, or Rikets ständer, when they were assembled. ...

Charles XIII was childless so in order to secure the succession to the throne, he adopted Prince Christian August of Augustenborg as his heir. He had been viceroy of Norway and commander-in-chief of the Norwegian army during its successful resistance against the Swedish invasion in 1808-1809. His great popularity in Norway was considered an advantage to the Swedish plans for the acquisition of that country. In addition, he had demonstrated his interest in a rapprochement between the two countries by refraining from invading Sweden during the conflict with Russia. As crown prince of Sweden, he changed his name to Carl August. 1808 was a leap year starting on Friday (see link for calendar). ... Year 1809 (MDCCCIX) was a common year starting on Sunday (link will display the full calendar). ...

He died on May 28, 1810. His autopsy confirmed that he had died of a stroke, but rumours had it that he had been poisoned by the Gustavians, more precisely by Marshal count Axel von Fersen, who was hideously murdered on June 20, 1810, by a mob as he was openly accused of having killed Charles August. May 28 is the 148th day of the year in the Gregorian calendar (149th in leap years). ... 1810 was a common year starting on Monday (see link for calendar). ... Count Axel von Fersen, dressed in the robes of a Swedish Privy Councilor, with the Knights Commander chains of the Royal Orders of the Seraphim and that of the Sword around his neck. ... June 20 is the 171st day of the year (172nd in leap years) in the Gregorian calendar, with 194 days remaining. ... 1810 was a common year starting on Monday (see link for calendar). ...

Next, a French marshal, Jean-Baptiste Bernadotte, Prince of Ponte Corvo, was adopted by Charles XIII and received the homage of the estates on November 5, 1810. Charles XIV John (Swedish: Carl XIV Johan), born Jean-Baptiste Bernadotte (January 26, 1763 – March 8, 1844) was King of Sweden and Norway (where he was known as Carl III Johan) from 1818 until his death. ... Ponte Corvo is a town in Latium, Italy. ... In several different regions of medieval Europe, and continuing in some countries[] down to the present day, the estates of the realm were broad divisions of society, usually distinguishing nobility, clergy, and commoners; this last group was, in some regions, further divided into burghers (also known as bourgeoisie) and peasants. ... November 5 is the 309th day of the year (310th in leap years) in the Gregorian calendar, with 56 days remaining. ... 1810 was a common year starting on Monday (see link for calendar). ...