Catherine came to power in a bloodless coup that later turned deadly.

When Elizabeth passed away in January 1762, her nephew Peter III and Catherine became king and queen. In an effort to make his mark on the country, he swiftly put a stop to Russia's conflict with Prussia, which greatly angered the country's military elite. Members of the lesser nobility were alienated by a liberal domestic reform agenda that was intended to improve the lives of the poor.

These disgruntled groups appealed to Catherine, who shared their concern about Peter's motives. As the tension increased, a plot to assassinate Peter developed. When the plot was discovered in July 1762, Catherine acted fast to get the backing of the nation's most potent military regiment and set up her husband's arrest.

On July 9, just six months after becoming czar, Peter abdicated, and Catherine was proclaimed sole ruler. However, what had began as a bloodless coup soon turned deadly. On July 17 Peter died, possibly at the hands of Alexei Orlov, the brother of Catherine’s current lover Gregory. Though there is no proof that Catherine knew of the alleged murder before it happened, it cast a pall over her reign from the start.