Decembrist revolt participant Decembrists
The Decembrist Revolt (Russian: Восстание декабристов, romanized: Vosstaniye dekabristov, lit. 'Uprising of the Decembrists') took place in Russia on 26 December [O.S. 14 December] 1825, following the sudden death of Emperor Alexander I.
Alexander's heir-presumptive,  Konstantin, had privately declined the succession, unknown to the court, and his younger brother Nicholas ascended the throne as Emperor Nicholas I. While some of the army had sworn loyalty to Nicholas, a force of about 3,000 troops tried to mount a military coup in favour of Konstantin. The rebels, although weakened by dissension between their leaders, confronted the loyalists outside the Senate building in the presence of a large crowd. In the confusion, the Emperor's envoy, Mikhail Miloradovich, was assassinated. Eventually, the loyalists opened fire with heavy artillery, which scattered the rebels. Many were sentenced to hanging, prison, or exile to Siberia. The conspirators became known as the Decembrists (Russian: декабристы, romanized: dekabristy).Union of Salvation and Union of Prosperity
At first, many officers were encouraged by Tsar Alexander I's early liberal reformation of Russian society and politics. Liberalism was encouraged on an official level, creating high expectations during the period of rapprochement between Napoleon and Alexander. The major advocate for reform in Alexander's regime was Count Mikhail Mikhailovich Speransky. During his early years in the regime, Speransky helped inspire the organization of the Ministry of the Interior, the reform of ecclesiastic education, and strengthening the government's role in the country's economic development. Speransky's role increased greatly in 1808. From then until 1812, when they feared him as a liberal similar to Napoleon and his invasion, Speransky developed plans for the reorganization of Russia's government. Because of increasing hostility, he was forced to flee into exile.
Returning from exile in 1819, Speransky was appointed as the governor of Siberia, with the task of reforming local government. In 1818, the tsar asked Count Nikolay Nikolayevich Novosiltsev to draw up a constitution. The abolition of serfdom in the Baltic provinces was instituted between 1816 and 1819. However, internal and external unrest, which the tsar believed stemmed from political liberalization, led to a series of repressions and a return to a former government of restraint and conservatism.
Meanwhile, the experiences of the Napoleonic Wars and realization of the suffering of peasant soldiers resulted in Decembrist officers and sympathizers being attracted to reform changes in society. They displayed their contempt of court by rejecting the court lifestyle, wearing their cavalry swords at balls (to indicate their unwillingness to dance), and committing themselves to academic study. These new practices captured the spirit of the times as a willingness by the Decembrists to embrace both the peasant (i.e., the fundamental Russian people) and ongoing reform movements from intellectuals abroad.
Pavel Pestel identified reasons for reform: