Peter I, also known as Peter the Great, was tsar of Russia from 1682 to 1725. He sought to modernize Russia and transform it into a major European power. Some of his key accomplishments included winning territory from Sweden, founding the new capital city of St. Petersburg, implementing domestic reforms in government, the military, and the alphabet, and attempting to secularize the Orthodox Church. However, his reforms met resistance, and his harsh treatment of opponents, including torturing his own son to death, undermined his goals and left Russia politically unstable after his death.