Brandenburg-Prussia - Establishment Under John Sigismund (1618)

Establishment Under John Sigismund (1618)

The Margraviate of Brandenburg had been the seat of the main branch of the Hohenzollerns, who were prince-electors in the Holy Roman Empire, since 1415. In 1525, by the Treaty of Krakow, the Duchy of Prussia was created through partial secularization of the State of the Teutonic Order. It was a vassal of the Kingdom of Poland and was governed by Duke Albert of Prussia, a member of a cadet branch of the House of Hohenzollern. On behalf of her mother Elisabeth of the Brandenburgian Hohenzollern, Anna Maria of Brunswick-Calenberg became Albert's second wife in 1550, and bore him his successor Albert Frederick. In 1563, the Brandenburgian branch of the Hohenzollern was granted the right of succession by the Polish crown. Albert Frederick became duke of Prussia after Albert's death in 1568. His mother died in the same year, and thereafter he showed signs of mental disorder. Because of the duke's illness, Prussia was governed by Albert's nephew George Frederick of Hohenzollern-Ansbach-Jägersdorf (1577–1603). In 1573, Albert Frederick married Marie Leonore of Jülich-Cleves-Berg, with whom he had several daughters.

In 1594, Albert Frederick's then 14-year-old daughter Anna married the son of Joachim Frederick of Hohenzollern-Brandenburg, John Sigismund. The marriage ensured the right of succession in the Prussian duchy as well as in Cleves. Upon George Frederick's death in 1603, the regency of the Prussian duchy passed to Joachim Frederick. Also in 1603, the Treaty of Gera was concluded by the members of the House of Hohenzollern, ruling that their territories were not to be internally divided in the future.

The Electors of Brandenburg inherited the Duchy of Prussia upon Albert Frederick's death in 1618, but the duchy continued to be held as a fief under the Polish Crown until 1656/7. Since John Sigismund had suffered a stroke in 1616 and as a consequence was severely handicapped physically as well as mentally, his wife Anna ruled the Duchy of Prussia in his name until John Sigismund died of a second stroke in 1619, aged 47.