The only comprehensive and reliable descriptions of four-handed fortress chess were published in 1850 and 1862 by the Russian master A. D. Petrov, who had first-hand experience with the game. An earlier source omits numerous details regarding the rules; later sources digesting Petrov’s description contain misconceptions and outright mistakes. The article at- tempts to refute the errors accumulated in the literature and accentuate the few minor points in the rules left uncovered by Petrov. An adaptation of the four-handed game for two players is provided.