Born a peasant in Livland (present-day Latvia), she was orphaned young and was working as a maid in a pastor's house when she married her first husband, Johann Kruse, a Swedish dragoon, in 1702. Russia was at war with Sweden, and Kruse shortly left with his regiment.
Marta was captured by Russian forces, and taken as a slave to a captain, who in turn made a gift of her to field-marshal Boris Sheremetev. By 1703, she was in the employ of the powerful statesman Aleksandr Menshikov. The tsar, Peter the Great, often visited Menshikov at his home, and during one of these visits, he met and became infatuated with Marta. He shortly renamed her Ekaterina (Catherine).
Marta/Catherine was sent to live in a palace with Peter's sister and other female relatives, and baptized into Orthodoxy. Peter also recognized the children she had borne him. In 1712, they married, with their own little daughters carrying the bride's train.
The margravine Wilhelmina of Bayreuth, who met the empress Catherine in 1718, remarked that she was "small, stumpy, very dark-complexioned, unimpressive, and ungraceful." Peter was devoted to Catherine, and more than a hundred of their letters have survived (Catherine's were taken by dictation, as she could not write Russian; it is not known if she was literate at all). In 1715, Catherine gave birth to a son, also named Peter, and Peter the Great pinned his dynastic hopes on this child. He moved to eliminate his eldest son, Aleksey, the adult son born to his first wife, Eudoxia. He demanded that Aleksey abdicate his rights to the throne and sent him away to a monastery. Aleksey fled Russia and lived in Austria and Italy until 1718, when he was lured back to Russia. There, Aleksey and all his friends and servants were brutally tortured. Aleksey shortly after died, at last freeing up the title of tsarevich for Peter and Catherine's little boy, Peter Petrovich. But in April 1719, little Peter died.
In 1724, Peter the Great arrested and executed Catherine's secretary, Willem Mons, on charges of corruption. According to rumors, Mons had had an affair with the empress, and one legend says Peter presented Mons' head on a platter to the empress. Despite this estrangement, Catherine was by Peter's side when he died in January 1725. Without a clear succession, the guards regiments rallied behind Catherine, who was acclaimed empress.
She had very little real power, mostly just signing documents sent to her by the officials. Catherine became ill, and in May 1727, she died, resulting in yet another succession crisis.
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