Read up on them. They're not the stuff of Masonry or of the Dan Brown novels and movies or any of that conspiracy theory nonsense.
They were warrior monks who followed a rule crafted by the proto-Cistercian and Doctor of the Cathoiic Church St. Bernard of Clairvaux. They fought nobly, but unfortunately got over their heads in wordly affairs (they were some of the first bankers), and were finally taken down by a French monarch who owed them money.
The main takeaway here is what St. Bernard intended for them. You'll find in his writings some very significant things about the complementary relationship of Christian theology and the Christian political order. He was a Catholic mystic of the first order but also a practical and martial saint. Hear ye him.