The Russian interregnum of 1825 began on with the death of Alexander I in Taganrog and lasted until the accession of Nicholas I and the suppression of the Decembrist revolt on . In 1823 Alexander secretly removed his brother Constantine from the order of succession, after Constantine informed Alexander he had no intention of ruling the Empire, and appointed his younger brother Nicholas heir presumptive. This unprecedented secrecy backfired with a dynastic crisis that placed the whole House of Romanov at peril. Only three men, apart from Alexander himself, were fully aware of his decision, and none of them was present in the Winter Palace when the news of Alexander's death reached Saint Petersburg on 1825.

Military governor Mikhail Miloradovich persuaded hesitant Nicholas to pledge allegiance to Constantine, who then lived in Warsaw as the viceroy of Poland. The State Council, faced with a legal Gordian Knot, concurred with Miloradovich; the civil government and the troops stationed in Saint Petersburg recognized Constantine as their sovereign – a sovereign who did not intend to reign. As The Times of London observed, the Russian Empire had "two self-denying Emperors and no active ruler".Chapman, pp. 46-47. Correspondence between Saint Petersburg and Warsaw, carried by mounted messengers, took two weeks. Constantine repeated his renunciation of the crown and blessed Nicholas as his sovereign but refused to come to Saint Petersburg, leaving the dangerous task of resolving the crisis to Nicholas alone.

Evidence of the brewing Decembrist revolt compelled Nicholas to act. In the first hour of he proclaimed himself Emperor of All the Russias. By noon the civil government and most of the troops of Saint Petersburg pledged allegiance to Nicholas but the Decembrists incited three thousand soldiers in support of Constantine and took a stand on Senate Square. Nicholas crushed the revolt at a cost of 1,271 livesNechkina, p. 117, analyzed different numbers from different sources. Nicholas released an estimate of 80 dead. The most credible report, according to Nechkina, was authored by S. N. Korsakov of Saint Petersburg police and counted 1,271 dead of whom 903 were civilians of low classes (, "the mob"). and became an undisputed sovereign. He ruled the empire in an authoritarian reactionary manner for 29 years.

The first historic study of the interregnum, Modest von Korff's Accession of Nicholas I, was commissioned by Nicholas himself. Memoirists, historians and fiction authors sought alternative explanations of the apparently irrational behaviour of the Romanovs. Conspiracy theorists named Alexander, Nicholas, Miloradovich and Dowager Empress Maria, alone or in various alliances, as the driving forces behind the events of November–December 1825.

Background

Four brothers

Four sons of Paul I

Alexander I of Russia, the eldest of four sons of Paul I, had no male issue; his legitimate daughters died in infancy. According to the 1797 Pauline Laws his childless brother Constantine had been heir presumptive since Alexander's accession. The third brother, Nicholas, followed him in the order of succession. Constantine and his legitimate wife Juliane of Saxe-Coburg-Saalfeld separated in 1799. Juliane returned to Germany and resisted any proposals to resume their marriage. Constantine's involvement in the Napoleonic Wars did not leave him with enough time or energy for a formal divorce. However, in 1815 he began an affair with Joanna Grudzińska, forcing him finally to divorce Juliane in order to marry Joanna.Schilder 1901, p. 91.

Constantine divorced Juliane in absentia on , 1820. On the same day Alexander appended the Pauline Laws with a principle that a marriage between a member of the House of Romanov and a person of lesser standing could not confer on the latter the rights of the House, and that their offspring were barred from the order of succession.Korff, pp.31-32. On of the same year, Constantine married Joanna, who was created Duchess of Łowicz.Korff, p. 32; Seton-Watson, p. 194. Constantine had no intention of ruling the Empire and retired to Warsaw as the viceroy of Congress Poland. According to Nicholas, Alexander told him of Constantine's decision to abdicate in 1819.Korff, pp. 24-26 and Schilder 1901, p. 91. According to Michael, the youngest of four brothers, he learned about it from Constantine in the summer of 1821.Korff, p. 33. In both cases the speakers emphasized extreme secrecy of the matter.

Korff wrote that Constantine's renunciation "was completed or, at all events, received its final arrangement" in the very end of 1821 when all four brothers reunited in Saint Petersburg.Korff, p. 36. On , 1822 Constantine sent "a humble petition" to Alexander, expressing his wish to pass the rights to the throne to the next in line, Nicholas.Korff, pp. 38-39, provides English translation. Two weeks later Alexander wrote to Constantine that the matter was still not resolved. The closing paragraph was especially ambiguous and could have been interpreted as leaving the final outcome in Constantine's hands: "It therefore remains to herself [Empress Maria] as well as to me ... to leave you fully at liberty to execute your irrevocable determination...".Korff, p. 40.

Secret manifesto

In the summer of 1823 minister of Ecclesiastical Affairs Alexander Golitsyn, acting on behalf of Alexander, asked Archbishop of Moscow Filaret to draft a formal manifesto that would seal the "final arrangement" made a year and a half earlier.Korff, pp. 42-43. The full text, in English, is provided in Korff, pp. 45-49. Alexander's usual speechwriter Mikhail Speransky was unaware of this.Korff, p. 43. Golitsyn instructed Filaret to lock the signed manifesto, in utmost secrecy, in the sanctuary of the Assumption Cathedral in Moscow. Filaret feared that a document locked in Moscow could not influence the transfer of power to the successor, which would normally take place in Saint Petersburg, and objected to Alexander. The tsar reluctantly agreed and ordered Golitsyn to make three copies and deposit them in sealed envelopes in the Synod, the Senate and the State Council in Saint Petersburg.Korff, p. 44. Although Filaret insisted that at least the existence of these envelopes must be made known to reliable witnesses, the whole affair "has been preserved as in a tomb, the Imperial secret involving the existence of the empire".

Alexander signed the manifesto in Tsarskoye Selo on , 1823 and brought it to Moscow himself on . According to Alexander's handwriting on the envelope it was "to be opened by the Diocesan of the See of Moscow and the General-Governor of Moscow in the cathedral of Assumption, before taking any other steps."Korff, p. 49. Four days later Filaret took the envelope inside the cathedral, showed Alexander's seal to three priests and locked the Manifest in the altar.Korff, p. 51. Governor of Moscow Dmitry Golitsyn remained unaware of the affair altogether.Korff, pp. 51-52.

The "Saint Petersburg copies", handwritten by Alexander Golitsyn and bearing Alexander's own handwriting on the envelopes, were filed three months later, raising short-lived speculations among the "completely ignorant dignitaries".Korff, p. 53. Apart from Alexander, only Aleksey Arakcheyev, Alexander Golitsyn and Filaret were certainly aware of the existence, contents and location of the manifesto and its copies.Schilder 1898, vol. 4 p. 388: "No one knew about the existence of the Act proclaiming Nicholas the Heir, apart from three statesmen: count Arakcheyev, prince A. I. Golitsyn and archbishop of Moscow Filaret." (). Modern historians contest this opinion, arguing that either Empress Maria or Miloradovich or both of them were fully aware of the Manifesto. According to Korff, Empress Maria was actively engaged in the events of 1821–1822 and knew of the "final arrangement"Alexander wrote of her as his principal advisor, if not the deciding voice, on succession problem - Korff, p. 40. but not its implementation. Constantine, Nicholas, Michael and Alexander's wife Elisabeth knew even less.Korff, pp. 41, 63, 65-66; Riasanovsky, p. 31. The reasons for unprecedented secrecy are unknown. Nicholas's bad reputation among the troops is a common explanation. Anatole Mazour wrote that Nicholas was "unacceptable to political circles and most unpleasant to military men"; as the inspector of the Guards he "aroused both the displeasures of higher officers and the hatred of the privates"; but Mazour also admitted that Constantine was "scarcely more agreeable to the military men".Mazour, pp. 158-159. Riasanovsky suggested that Alexander wanted to retain freedom to change the 1823 manifesto at will.Riasanovsky, p. 31.

Conspiracy After the end of the Napoleonic Wars the Russian economy, ravaged by the Continental SystemMazour, pp. 12-15, analyzed the effects of the Continental System on agriculture and industry. and Napoleon's invasion, slid into a continuous economic crisis. Grain exports were high in 1816–1817, but in 1818–1819 Western European crops recovered and Russian exports plummeted.Mazour, pp. 17-18. Landed gentry tried to restore lost income through enclosures and driving away redundant serf peasants, but Alexander outlawed the "emancipation" of serfs without land.Mazour, pp. 3-6, analyzed Alexander's motives for the 1808 ban. Economic downfall fuelled radical opposition inside the Russian nobility: "it was Alexander's failures to live up to their hopes that led them to take on the task themselves".Wortman, p. 128.

The imperial treasury was bankrupted by rising state debt and falling revenues. Alexander was aware of the crisis but never tackled its root cause, the oversized peacetime army of 800,000 men.Kagan, pp. 11, 34. Alexander expected future wars in Southern Europe and the Middle East,Kagan, p. 34. and feared that mass dismissal of veteran soldiers would cause insurrection. He could not let them go: they were not needed in their native villages, and there were no jobs in the cities. Instead of reducing the army to an affordable peacetime size, Alexander tried to cut spending through the establishment of self-sustaining military settlements, which failed "from start to finish".Mazur, pp. 41-45. He replaced expensive field maneuvers with drill exercise and parades, alienating experienced commanders and contributing to dissatisfaction of the nobility.Kagan, p. 33.

The first secret organization aspiring to change the system was formed by the veterans of Napoleonic Wars in February 1816.Mazour, p. 66. Their aims varied from establishing a constitutional monarchy to "getting rid of foreigners and alien influence".Mazour, p. 68. Some even considered murdering Alexander I after Sergey Trubetskoy reported a rumour that Alexander was planning to incorporate western provinces into Congress Poland.Mazour, p. 71. In 1818 the organization was reformed into the Union of Prosperity. In the same year Pavel Pestel, the most radical conspirator, relocated to Ukraine and began actively recruiting Army officers, the core of the future Southern Society.Mazour, pp. 74-79.