This is an excerpt from the Wikipedia article about Catherine I: "Catherine and Peter married secretly in 1707. They had nine children, two of whom survived into adulthood, Yelizaveta (born 1709) and Anna (born 1708). Peter had moved the capital to St Petersburg in 1703. While the city was being built he lived in a three-room log cabin with Catherine, where she did the cooking and caring for the children, and he tended a garden as though they were an ordinary couple. The relationship was the most successful of Peter's life and a great number of letters exist demonstrating the strong affection between Catherine and Peter. As a person she was very energetic, compassionate, charming and always cheerful. She was able to calm Peter in his frequent rages and was called in to attend him during his epileptic seizures.
Catherine continued to accompany Peter on his Pruth campaign in 1711. There Catherine was said to have saved Peter and his Empire. Surrounded by overwhelming numbers of Turkish troops, Catherine suggested before surrendering, her jewels and those of the other women be used in an effort to bribe the Grand Vizier Baltaji into allowing a retreat. Baltaji allowed the retreat, whether motivated by a bribe or considerations of trade and diplomacy. In any case Peter credited Catherine and proceeded to marry her again (this time officially) at Saint Isaac's Cathedral in St. Petersburg on 9 February 1712."