The Templars were orginally an order of knights founded in 1118 and approved by (I think it was) Baldwin II; they were to defend the Temple in Jerusalem. At that time they were a mendicant order and enforced the "poverty-chastity-obedience" rule. Over the next couple hundred years, the order became more and more powerful, mostly by the simple fact that various Popes and Kings exempted them from taxes and tithes because of the "Temple at Jerusalem" connection.

One of the Phillips (of France) needed money, and decided that the Templars (who by that time were sort of the "bankers of Europe") had it. He began an investigation of the Order, and even convinced the Pope to issue a Bull against the order (which was done on March 22, 1312). With that, the Order had a full-blown persecution. They were accused of the usual sexual "depravities" and of worshiping the idol/demon Baphomet. Most of them were tortured and burned; some apparently did escape to England; all of the property and money the Church and the governments could get their hands on was comfiscated. England, as I remember it, took what money the order still had and turned at least some of the Order over to the continental Church.

Up until about 1908, the criticisms against the Templars were pretty much taken as proven fact by scholars. Since that time, however, it's thought that the Order was more sinned against than sinning.

The above is from memory. I simply don't subscribe to a conspiracy theory about the Templars; there are too many other, more provable, things out there today.