How the heck did SOE achieve such faction loyalty?

[GuyFawkes]

Just to add that you can talk to the opposition, not in a spy type of way (does happen though) which adds to the rivalry and camaraderie. Its similar to how boxers once they are in the ring they just want to destroy their opponent, but once its over they shake hands and no hard feelings. But if they have a rematch its back to being total enemies and wanting to kill each other again.