Some say that it stems from when the King of France declared the Knights Templar illegal, thereby cancelling out his large debt to their bank. Their leader, Jacques DeMolay, was arrested on Friday the 13th 1314.Other lore surrounding this, is that the:
Shroud of Turin is actually from DeMolay.
Most of the Templar fleet escaped to Scotland and Portugal.
Some of the Templar Fleet became Pirates, robbing only countries ships that were aligned with the Pope.
The "Jolly Roger" flag was named after a Templar King of Sicily.
Templar Sir Henry Sinclair sailed to North America before Columbus.
Roger Moore played Simon Templar in "The Saint", with the open showing reading books on the Templar Knights as a boy.
FROM WIKIPEDIA: As European support for the Crusades had dwindled, other forces were at work which sought to disband the Order and claim the wealth of the Templars as their own. King Philip IV of France, deeply in debt to the Templars, had Molay and many other French Templars arrested in 1307 and tortured into making false confessions. When Molay later retracted his confession, Philip had him burned upon a scaffold on an island in the River Seine in front of Notre Dame de Paris in March, 1314.[4] The sudden end of both the centuries-old order of Templars and the dramatic execution of its last leader turned Molay into a legendary figure.