Peter III of Russia
Empress Elizabeth arranged for Peter to marry his second cousin, Sophia Augusta Frederica (later Catherine the Great), daughter of Christian August, Prince of Anhalt-Zerbst and Johanna Elisabeth of Holstein-Gottorp. The young princess formally converted to Russian Orthodoxy and took the name Ekaterina Alexeievna (i.e., Catherine). They married on 21 August 1745. The marriage was not a happy one but produced one son, the future Emperor Paul, and one daughter, Anna Petrovna (20 December 1757 – 19 March 1759). Catherine later claimed that Paul was not fathered by Peter: that, in fact, they had never consummated the marriage. During the sixteen years of their residence in Oranienbaum, Catherine took numerous lovers, while her husband did the same in the beginning.
Peter III of Portugal
The couple married on 6 June 1760. At the time of their marriage, Maria was 25 and Pedro was 42. Despite the age gap, the couple had a happy marriage. Peter automatically became co-monarch (as Pedro III of Portugal) when Maria ascended the throne, as a child had already been born from their marriage. The couple had six children and a stillborn baby.