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.
Catherine the Great
Although Catherine did not descend from the Romanov dynasty, she had descended from the Rurik dynasty, which preceded the Romanovs. She succeeded her husband as empress regnant, following the precedent established when Catherine I succeeded her husband Peter the Great in 1725. Historians debate Catherine's technical status, whether as a regent or as a usurper, tolerable only during the minority of her son, Grand Duke Paul. In the 1770s, a group of nobles connected with Paul (Nikita Panin and others) considered a new "coup" to depose Catherine and transfer the crown to Paul, whose power they envisaged restricting in a kind of constitutional monarchy. Nothing came of this, however, and Catherine reigned until her death.