As a financially successful author, editor, and playwright, Gorky gave financial support to the Russian Social Democratic Labour Party (RSDLP), as well as supporting liberal appeals to the government for civil rights and social reform. The brutal shooting of workers marching to the Tsar with a petition for reform on 9 January 1905 (known as the "Bloody Sunday"), which set in motion the Revolution of 1905, seems to have pushed Gorky more decisively toward radical solutions. He became closely associated with Vladimir Lenin and Alexander Bogdanov's Bolshevik wing of the party, with Bogdanov taking responsibility for the transfer of funds from Gorky to Vpered. It is not clear whether he ever formally joined, and his relations with Lenin and the Bolsheviks would always be rocky. His most influential writings in these years were a series of political plays, most famously "The Lower Depths" (1902). While briefly imprisoned in Peter and Paul Fortress during the abortive 1905 Russian Revolution, Gorky wrote the play "Children of the Sun", nominally set during an 1862 cholera epidemic, but universally understood to relate to present-day events. He was released from the prison after a European-wide campaign, which was supported by Marie Curie, Auguste Rodin and Anatole France, amongst others.