William I of Württemberg
On 24 January 1816, in Saint Petersburg, he married his first cousin, Grand Duchess Catherine Pavlovna of Russia (1788–1819), daughter of Emperor Paul I of Russia (1754–1801) and Princess Sophie Dorothea of Württemberg (1759–1828). The couple had two children:
Duchy of Prussia
On 1 March 1526 Albert married Princess Dorothea, daughter of King Frederick I of Denmark, thereby establishing political ties between Lutheranism and Scandinavia. Albert was greatly aided by his elder brother George, Margrave of Brandenburg-Ansbach, who had earlier established the Protestant religion in his territories of Franconia and Upper Silesia. Albert also found himself reliant on support from his Jagiellonian uncle Sigismund I of Catholic Poland, as the Holy Roman Empire and the Roman Catholic Church had banned him for his Protestantism.