Frederick William, Duke of Courland

Friedrich Wilhelm Kettler was born in 1692 in Mitau (now Jelgava) in the family of Friedrich Casimir and his second wife Elizabeth Sophia. At the age of five, after his father's death, on 22 January 1698 he was appointed as the Duke of Courland and Semigallia, however, until the age of majority state was governed by his mother and his uncle, Ferdinand Kettler, who resided in Danzig.

When in 1701 Semigallia was occupied by the Swedes, Friedrich Wilhelm and his mother went to the court of Frederick I, the future first king in Prussia. He stayed in Prussia until 1709 when, after Russian victories against Sweden, he was engaged at the age of 17 to Anna of Russia, the daughter of Tsar Ivan V (half brother of Peter the Great). The Council of the Duchy in 1709 recognized Friedrich Wilhelm as an adult and the young Duke arrived in Libau (now Liepāja) in 1710.

He married Anna on 11 November 1710 (31 October, after the old style) in a grand wedding held in the new Russian capital of Saint Petersburg, which presented the power of the emerging Russian Empire and its court brilliance.^[1] However, on the way back from Saint Petersburg, Friedrich Wilhelm died on 21 January 1711 in the postal station, and his widow Anna, together with the Duke's corpse, arrived in Mitau only on 4 March.

After his death, Anna took on the regency of the duchy. In 1730 she became Empress of Russia and the duchy passed to Friedrich Wilhelm's uncle Ferdinand Kettler, but was de facto controlled by Russia. It was restored to independence in 1737, when it passed to the lover of Tsarina Anna, Ernst Johann Biron.

At the same time in the duchy began the epidemic of Great plague, which killed a large part of the population.^{[citation needed]}