Interesting article from Catholic Answers magazine.
Thankfully, available online.
A taste from somewhere in the middle of the article:
Membership in the order grew as a result of the writing and preaching of Bernard of Clairvaux (1090–1153). Bernard wrote a treatise entitled On the Praise of the New Knighthood in which he exhorted knights to renounce the dangers of fighting for temporal reasons, which threaten the soul, in exchange for fighting for Christ and the Church, in which to die is to gain eternally:
Life indeed is fruitful and victory glorious, but according to holy law death is better than either of these things. For if those are blessed who die in the Lord, how much more blessed are those who die for the Lord?
As the order grew in membership it also increased in prominence and influence in the Holy Land and Europe; by 1150 the Templars could muster 600 knights, which, combined with the Hospitallers, amounted to half the total available knights in the Latin East. Their power in Christendom was rooted in the 9,000 feudal lordships and manors they owned, which provided a large base of resources and financial influence. Templar houses became known as important financial centers in Europe and served as places of deposit for Crusaders traveling to the Holy Land. They inaugurated the first primitive system of ATMs, allowing those who deposited funds in a Templar house in Europe to withdraw that amount minus a fee at Templar houses in the Latin East.