"While fighting to gain control of the province of Bactria, Alexander the Great was confronted by the swarming tactics of Scythian horse-archers. His primary unit--the Macedonian Phalanx--could not cope with the mobile, pulsing, ranged attacks of these units, which would swarm around his fixed formations like wasps, darting in, firing arrows from a standoff range and quickly retreating. Alexander pioneered what remains today the US Army's counter-swarm (though normally labeled counter-guerrilla) tactic: Find, Fix and Defeat."
Interesting. I don't know how authoritative the author is on current protest tactics, but he's informative about what US troops will face in the coming years. (The bit on Iranian troops training with RPGs and sniper rifles from two-man motorcycle teams was worth the price of admission all its own.)