The main, heavy cavalry force of the armies of the Byzantine Empire (the east roman empire).
Well trained, and generally far superior to other cavalry forces of the time, the cataphracts were the mainstay of the Byzantine Empire. Equipment varied, but would most often include heavy armour, lances, swords and bows which were fired from the saddle. The cataphracts would act as a heavy shock force, supported by light and heavy infantry and archers.
Although usually outnumbered by masses of untrained warriors, the Byzantine army prevailed thanks to intelligent tactics and good discipline. The army was backed by a network of spies and secret agents that provided information about enemy plans and could be used to bribe or otherwise deflect aggressors.
The cataphract cavalry were one of the main reasons that the Byzantine Empire lasted as long as it did, before it fell to moslem invaders (led by the Turkish sultan Mehmet II) in May 1453.