In 1307, a powerful order of militant Catholic monks controlled a lot of the Western European economy.

In addition to guarding pilgrims on their way to the Holy Land, the Knights Templar also ran gold banks. A traveler could deposit gold with the Knights in England, receive a receipt, and collect their gold in Italy. It prevented robbers from stealing the heavy gold en route. 

But the King of France, Philip IV, ran into money troubles, so he raided the monks. He teamed up with the pope to torture the knights into giving up. The Grand Master was even burned at the stake. 

Historian John Schmidt says that this event very well may have been the origin of our Friday the 13th superstition.