Task: Text Categorization
Input (English): One of their leaders expressed their ideology in the pamphlet "Truth. "  Drawn from such organizations as the Union of Welfare and the Union of Salvation, their acts were immortalized in a special issue of the periodical The Northern Star. Some ten days after their initial military operation had been defeated another force of 1,100 men in Chernigov led by the Southern Society rose up to challenge the ascension of Nicholas I. Led by such men as Pavel Pestel, they sought to set Prince Trubetskoy up as provisional dictator until Constantine could take power. FTP, identify this group of Russian revolutionaries who took took name from the month in which they planned their uprising.
Output (English): History