Swarming in history
Enthusiasts of swarming sometimes apply it to situations that have superficial similarities, but really do not qualify as swarms. While swarms do converge on a target, not every military action, where multiple units attacked from all sides of a target, constitute swarming. Other conflicts, especially historical ones, fit a swarming paradigm, but the commanders involved did not use the concept. Nevertheless, historical examples help illustrate what modern analysts do and do not consider swarming.
Some historical examples with at least some aspect of swarming include:
Siege of Samarkand
At the siege of Samarkand, Spitamenes used Bactrian horse archers in effective swarming attacks against a relief column sent by Alexander the Great. Bactrian horse archers surrounded various Macedonian phalanxes, staying out of range of their melee weapons, and shot arrows until they had no more. The archers would then withdraw to a supply point, but another swarm of horse archers would sometimes replace them, and sometimes attack elsewhere. The Bactrians eventually caused the phalanx to break formation, and destroyed it. Alexander recognized his forces could not directly combat horse archers, but that the horse archers needed resupply of provisions, horses, and arrows. Alexander split his forces into five columns and began building fortifications in the areas where the Bactrians had resupplied. Eventually, his anti-swarm tactics worked: cut off from resupply, the Bactrians had to meet the Macedonian phalanx, which were vastly superior in melee. Alexander made it priority to engage guerillas or other light mobile forces. Spitamenes was effective as long as his force were mobile, and he had adequate communications with mounted couriers. Once he was forced into direct battle with heavy forces, he literally lost his head. At the Battle of the Jaxartes River, Alexander once again faced swarming tactics from an army of Scythian horse archers. Alexander sent a unit of heavy cavalry ahead of his main line. As expected, the Scythian horsemen surrounded the detached cavalry. At the right moment, Alexander's cavalry reversed direction and pushed half of the Scythians straight into the main phalanx of Alexander's army, where they were slaughtered. Upon seeing this, the remaining half of the Scythian army retreated from the battle.
Mongols under Genghis Khan practiced an equivalent of swarming, partially because their communications, which used flags, horns, and couriers, were advanced for the time. Also one of the standard tactics of Mongol military was the commonly practiced feigned retreat to break enemy formations and to lure small enemy groups away from larger groups and defended positions for ambush and counterattack. Genghis Khan used the Yam system, which established a rear line of points for supplies and for remounts of fast-moving couriers. The remount system allowed horsemen to move much faster than the couriers of opponents without them. These couriers kept the Mongol senior and subordinate commanders informed, such that they could make fast decisions based on current information. In modern terms, the courier system provided the means of getting inside the opponent's OODA loop. With fast communications, the Mongols could make decisions not just on what they could see locally, but with that information oriented within the overall situation. They could then decide and act while the enemy were still waiting for information. Outnumbered Mongols could beat larger forces by faster communications, which allowed units to withdraw and regroup while other groups continually stung the enemy, withdrew in turn, while the earlier group again hit the enemy.