Background
Kettler was born near Anröchte, Kreis Soest, of an old Westphalian noble family and the ninth child of the German knight Gotthard Kettler zu Melrich (mentioned 1527–1556) and his wife Sophie of Nesselrode.
Kettler was born near Anröchte, Kreis Soest, of an old Westphalian noble family and the ninth child of the German knight Gotthard Kettler zu Melrich (mentioned 1527–1556) and his wife Sophie of Nesselrode.
Gotthard"s older brother Wilhelm Kettler was bishop of Münster from 1553 to 1557. In 1554 Gotthard Kettler became Komtur of Dünaburg, and in 1557 Komtur of Fellin. In 1559, during the Livonian War (1558–1582) he succeed to Wilhelm von Fürstenberg as a Master of the Teutonic Order in Livonia.
On the basis of the Treaty of Vilnius (28 November 1561), he created the Duchy of Courland and Semigallia as a vassal state of the Grand Duchy of Lithuania, which was soon merged into the Polish-Lithuanian Commonwealth.
On 11 March 1566 Kettler married Anna, Duchess of Mecklenburg, daughter of Duke Albert VII of Mecklenburg-Güstrow and Princess Anna of Brandenburg. After Dukes proposal in 1567 Regional assembly (landtag) took decision to build 70 new churches and 8 schools in the remote areas of Duchy where many peasants still lived and died unbaptized.
He died on 17 May 1587 in Mitau (Polish Mitawa, Latvian Jelgava), aged 70. His heirs ruled in Courland until 1737.
