Alexander I was the Emperor of Russia from 1801 to 1825. He is known for his role in the Napoleonic Wars, where he initially allied with Napoleon Bonaparte but later became one of the key figures in the coalition that defeated him. Alexander I implemented several reforms in Russia, including educational and administrative changes, and he promoted the idea of a constitutional monarchy. During his reign, Alexander I also focused on foreign policy, expanding Russian territory and influence. He played a significant role in the Congress of Vienna in 1815, which aimed to restore stability in Europe after the turmoil of the Napoleonic Wars. His leadership helped shape the political landscape of Europe in the early 19th century.