"O Lord, the foursome, the horsemen!"
The Four Horsemen
are described in the Books of Revelations; they arrive during the Apocalypse, just before the Last Judgement. The white horse is ridden by Conquest, the red by War, the black by Famine and the 'pale' horse is ridden by Death.
For more on Russian eschatology, see the bookmark to Page 644, "the end of the world".