YOU SEE THE TEMPLARS HAD A GOOD DEAL: ROOM AND BOARD.
And you see ISIS doing the same.
And we see Ukrainian Volunteers dong the same.
And you saw american revolutionary soldiers doing it.
And you saw european soldiers throughout history do it.
The central problem of raising an army is not weapons, it is merely the money necessary to supply room and board for those men who prefer to fight for change rather than do whatever it is at their disposal.
If you ask men to bring a weapon, they will. But you must be able to feed, shelter, and direct them.
Once you have men and weapons, you have an army, and an army can take whatever it wants or needs. And by the act of merely taking, it disrupts the economy so significantly that little else need be done.
What the Islamists do well is (a) live on few resources, and (b) distribute money effectively through channels, and (c) make use of a vast surplus of men.
Western men are in surplus. Money, Distribution, and Communication are not complicated.
Moral authority. A set of Demands, A plan. Room and Board.
Simple men think in tactics. General think in logistics.
You see, the more advanced an economy, the more fragile it is.