Mithras was a god of soldiers, Greco-Roman.
Derived from the Indian-Persian model, he was especially prominent among the military throughout the Roman Empire during the first and second centuries AD as a god symbolizing loyalty and truth.
His rituals were performed in underground, cave-like temples, the mithraeum, and involved the sacrificing of a bull.
Under Roman influence, Mithraism was an exclusive male cult. A.G.H.
Jordan, Michael, Encyclopedia of Gods, New York, Facts On File, Inc. 1993, p. 167