Eventually they fell when the order as a whole, which by that time had thousands of monasteries and hundreds of thousands of knights spread across Europe and the Middle East, was accused of witchcraft, sadistic sexual practices, and other unacceptable behavior. Friday the thirteenth as the "evil omen" day we know started with the Templar Knights. The monarchy and church of the time sent out an order on a Friday the thirteenth for all Templar Knights to be arrested and/or killed. (Think Star Wars Episode 2, when all the clones suddenly turn on the Jedi. Yeah, it was kinda like that.)
Those not slain were put to the question (a.k.a. torture) and made to confess their crimes.
Most people today recognize the sham that was the Trial of the Templars. It was very similar to the Salem Witch Trials. Though there might have been some questionable behavior (an order that large is bound to have a few twisted apples) the majority of these knights chose death rather than admit to false accusations. A very small number did confess under torture, but immediately afterward recanted, saying it was only their physical weakness in the face of unbelievable pain that made them say what their torturers demanded.
These circumstances are a pretty good indication that the majority of the accusations were false. If one studies the history, it also becomes clear that their accusers had a whole lot to gain by bringing down the Order of Knights, which were richer than either the monarchy or the Church in terms of both coin and land ownership.
I love the middle ages, the Crusades (in which the Templars played a large part) and anything that has to do with knights and castles. I'm thinking of starting a project set against the backdrop of this time period and the Order of the Knights Templar. I'd love to get some good-hearted, wonderfully conflicted characters and drop them into the middle of all this. There'd be romance, battles, intrigue, politics--all the best parts of the middle ages!
What do you think? Is this something you'd be interested in reading? (Just gauging interest here! :D)