Tsar Alexander II of Russia ruled from 1855 to 1881 and is best known for his significant reforms aimed at modernizing Russia. He is often called the "Tsar Liberator" because he abolished serfdom in 1861, freeing millions of peasants from bondage and allowing them to own land. In addition to ending serfdom, Alexander II implemented various reforms in the military, education, and local government. His reign faced challenges, including political unrest and opposition from revolutionary groups. Ultimately, Alexander II was assassinated in 1881, which marked a turning point in Russian history and led to increased repression.