Several revolutions, uprisings, assassinations of Tsars, and power takeovers in St. Peterburg had shaped the course of history in Russia and influenced the world. In 1801, after the assassination of the Emperor Paul I, his son became the Emperor Alexander I. Alexander I ruled Russia during the Napoleonic Wars and expanded his Empire by acquisitions of Finland and part of Poland. His mysterious death in 1825 was marked by the Decembrist revolt, which was suppressed by the Emperor Nicholas I, who ordered execution of leaders and exiled hundreds of their followers to Siberia.