then disconnects. This reflects normal human behaviour even in peacetime: busy leaders pass new recruits on to colleagues. In wartime, and with an enemy that might resort to vertex-order attacks, the incentive to delegate is even greater. Thus a terrorist leader who gets an offer from a wealthy businessman to finance an attack might simply introduce him to a young militant who wants to carry one out. The leader need now maintain communications with at most one of the two.

Delegation on its own is rather slow; it takes dozens of rounds for delegation to ‘immunise’ a network against vertex-order attack. If a vanilla scale-free network is going to be exposed to either a vertex-order or centrality attack from the next round, then drastic action (such as clique formation) is needed at once; else it will be disconnected within two or three rounds. Slower defences like delegation can however play a role, provided they are started from network formation or a reasonable time period (say 20 rounds) before the attack begins.

It turns out that the delegation defence, on its own, is rather like the rings of dining steganographers. Network fragmentation is postponed (about 14 rounds with the parameters used 