Originally Posted by Kevin-SFBucks

Two possibilities:

The Knights Templar were a monastic military order founded in Jerusalem in 1118 C.E., whose mission was to protect Christian pilgrims during the Crusades. Over the next two centuries, the Knights Templar became extraordinarily powerful and wealthy. Threatened by that power and eager to acquire their wealth, King Philip secretly ordered the mass arrest of all the Knights Templar in France on Friday, October 13, 1307 - Friday the 13th.