Final answer:
Catherine the Great became the ruler of Russia after organizing a coup against her husband, Peter III. Though she sought modernization, her rule stayed authoritarian, and Russia was left underdeveloped compared to Western nations at the time.
Step-by-step explanation:
Empress Catherine II, known as Catherine the Great, became the leader of Russia following a coup that ousted her husband, Peter III. Catherine's rise to power in 1762 was not through a traditional line of succession, as her husband was the Emperor of Russia. However, with the support of the Imperial Russian Guard and influential associates within the court, Catherine was able to overthrow Peter and declare herself the sole ruler of Russia. Her reign is noted for the expansion of Russian territory and attempts at modernization and westernization of the country. Despite her enlightened stance on certain issues, her rule remained largely authoritarian, and she did not fully integrate Western liberal reforms into her governance.
The advancement of Russia's interests during her tenure included strategies to expand into fertile riverlands and ambitions to weaken the Ottoman empire. Catherine's legacy is a complex one, where efforts to modernize Russia clashed with the imperatives of maintaining absolute monarchical control, resulting in Russia remaining economically underdeveloped relative to Western standards of the same period.