Historians have generally agreed that a revolutionary movement was born during the reign of Alexander I. Young officers who had pursued Napoleon into Western Europe came back to Russia with revolutionary ideas, including human rights, representative government, and mass democracy. The intellectual Westernization that had been fostered in the eighteenth century by a paternalistic, autocratic Russian state now included opposition to autocracy, demands for representative government, calls for the abolition of serfdom, and, in some instances, advocacy of a revolutionary overthrow of the government. Officers were particularly incensed that Alexander had granted Poland a constitution while Russia remained without one. Several clandestine organizations were preparing for an uprising when Alexander died unexpectedly in 1825. Following his death, there was confusion about who would succeed him because the next in line, his brother Constantine, had relinquished his right to the throne. A group of officers commanding about 3,000 men refused to swear allegiance to the new tsar, Alexander's brother Nicholas, proclaiming instead their loyalty to the idea of a Russian constitution. Because these events occurred in December 1825, the rebels were called Decembrists. Nicholas easily overcame the revolt, and the Decembrists who remained alive were arrested. Many were exiled to Siberia.