During the Russian Revolution of 1905, a reactionary, anti-Semitic group called the League of the Russian People, commonly referred to as the Black Hundreds, was secretly formed and unofficially sanctioned by the government. Made up primarily of landowners, wealthy peasants, bureaucrats, and police, the Black Hundreds attacked and killed revolutionaries in the Russian provinces. While organized local massacres (pogroms), especially of Jews, had been a regular part of Russian life since the assassination of Czar Alexander II (1818-81), they became particularly violent and frequent under the "respectable" leadership of the Black Hundreds, who instigated pogroms in more than 100 cities. In Odessa, a four-day slaughter of Jews and others occurred before order was restored. These ghastly repressions encouraged Russia's autocratic leaders to delay the enactment of the new constitution achieved in the 1905 revolution.