The "Fall of Civilization" is a modification for Age of Empires III. The mod will reconstruct 14 Medieval civilizations across the globe in terms of appearance(of UB & UU),unique units,and unique strength.
Kataphraktoi is a Byzantine Heavy Cavalry, and Athanatoi is its upgrade. Athanatoi, on history, is a unit from tagmata (Emperor's body guard) which is the best equipted and best trained unit in the empire.