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 of Castile
Peter began his reign when almost sixteen years old and subjected to the control of his mother and her favourites. He was to be married to Joan, daughter of Edward III of England; on their way to Castile, however, her retinue travelled through cities infested with the Black Death, ignoring townspeople who had warned them not to enter their settlements. Since the plague had not yet entered England, it is likely that they understandably underestimated the danger. Joan, fourteen years old and Edward's favorite, by his own admission, soon contracted the disease and died.
Though at first controlled by his mother, Peter emancipated himself with the encouragement of the minister Alburquerque. Becoming attached to María de Padilla, he married her in secret in 1353. María turned him against Alburquerque, who fled to Portugal.