[2 Kool 2 Be 4-Gotten]

On October 13th, 1307, King Philip had all the Templars arrested on the grounds of heresy

Bit of trivia. I believe this was a Friday, and therefore is the direct link to the Friday 13 superstition.

[ExSoldier]

Wait, I thought that legend ocurred because the French Revolution began on Friday the 13th in 13something and it started simultaneously all over France because the Masons/Templars had it preplanned that way. They had an old enemity with the Knights of Malta and those folks were specifically targeted in the initial round of fighting. I'm not a "world history" guy (although I have taught it in the past) when I teach core curriculum, I'm more of an American History person; and American Government.

[dread78645]

I believe this was a Friday, and therefore is the direct link to the Friday 13 superstition.

It was.
As for the source of the superstition, it's as good as any reason I've heard.