Tsar Alexander I of Russia reigned from 1801 to 1825. He was born on December 23, 1777, and became known for his role in the Napoleonic Wars. Initially, he was an ally of Napoleon Bonaparte, but later led a coalition against him, contributing to Napoleon's defeat in 1814. During his reign, Alexander I implemented several reforms aimed at modernizing Russia, including educational and administrative changes. He also 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. Alexander I died on December 1, 1825.