Military Orders
Influence
Political Influence
The Hospitallers and Templars were the closest thing the Latins had to a standing army in Outremêr. Especially in the 13th century, they commanded many of the most important castles and at times negotiated agreements with Muslim lords directly. They were natural rivals, but generally kept their rivalries in check, though their restraint did break down from time to time, most notably in the War of St. Sabat.
Influence in Europe
From early in the history of the Orders, European lords made pious donations to the Orders. The result was that there were soon Templar and Hospitaller castles dotting the landscape of western Europe. These commanderies (a Templar term) provided both men and money to the Holy Land, but they had a secondary effect of involving the Orders in European politics.
Think of Ivanhoe (if you haven’t read it yet, go read it now, then come back here <grin>). By the 13th century, the Templars and Hospitallers both had significant holdings, especially in England and France. A little later, the Teutonic Knights would become a major power in eastern Europe. A great many knights never even saw the Holy Land, spending their entire career in a European commanderie.
The Orders were directly under papal authority, answerable to no baron, no duke, and no king. They generally behaved themselves and were never a key power in any particular power in a European conflict, but neither could they be completely ignored.
Also over the course of the 13th century, the Orders became increasingly involved in financial transactions. This was particularly true of the Templars. As independent agents, the Orders were politically neutral and were protected by the Church. Having so many connections in the East, they were a natural choice for the transfer of funds from the West to Outremêr. They got into the banking business by handling financial transactions either directly connected with a crusade, or otherwise connected with the defense of the Holy Land. As the century wore on, they dealt with financial transactions on a wider scale.
This sort of activity, along with their political independence, made them an obvious target for an ambitious king jealous of his royal prerogatives. At the turn of the century, France had just such an ambitious and jealous king in Philip IV. With any pretense of defending the Holy Land gone, the Templars were vulnerable to royal attack.