With its origins in the 14th Century, the Order of St. Dumas was a small army of warrior priests dedicated to visiting wrath upon infidel foes during the Crusades. Similar in its credo to the Knights Templar, the Order defied Papal sanction and broke away from the Catholic Church, ultimately taking its mission underground while secretly amassing great wealth and power. The order demanded unwavering obedience from its members. Anyone who dared to betray its secrets was slain by the Order's "avenging angel," Azrael. This merciless warrior was trained from infancy using the System, an arcane mix of mental and physical conditioning through post-hypnotic suggestion. Over the centuries that followed, the Order's numbers dwindled and its mission became increasingly tainted by the greed of its remaining devotees. College student John Paul Valley inherited the mantle of Azrael from his father when the latter was killed in the Order's service.
Their numbers have become small. There are fewer than a dozen of them left, scattered about a few cities in Europe and America.
Valley briefly served the remaining acolytes of St. Dumas; however, with Batman's help, he managed to escape the psychic bonds of the System. When he learned the full story of the horrific procedures that forged him into Azrael, Valley destroyed every last vestige of the Order. The death of John Paul Valley, the last, albeit unwilling, member of the Order of St. Dumas, brought to an end this bizzare and sinister remnant of a bygone era.
The order of St. Dumas is revealed to be one of the 5 wealthy and powerful families who founded Gotham City. The Waynes banished the Dumas family and erased their contributions to Gotham, which started a centuries old blood Feud. The Dumas family went into hiding and changed their name.