Killer Swarms

Today marks the bicentennial of the culminating catastrophe that befell the Grande Armée as it retreated from Russia. This past weekend one of the French Emperor’s descendants, Charles Napoleon, traveled to Minsk in Belarus to attend ceremonies commemorating the disaster at the nearby Beresina River crossing, where thousands died — many by drowning — in a final, panicked rout in freezing weather. Bonaparte had marched deep into Russia with nearly half a million soldiers; he returned with less than 25,000.

Given that Napoleon was the great captain of his time — perhaps of all time — and that his armies had conquered and held most of Europe, the tragic events on the Beresina demand explanation. His defeat is something of a puzzle, too, as the Grande Armée won the campaign’s pitched battles fought at Smolensk and Borodino. Harsh winter weather, the commonly assumed culprit, cannot explain the result either; the first frost didn’t arrive to bedevil the retreat until just a few weeks before the Beresina crossing.

The answer to the puzzle is that Napoleon and his forces were beaten by what a young Russian hussar, Denis Davydov, called his "indestructible swarm" of Cossacks and other raiders who constantly harried the French columns on the march. They also struck relentlessly, repeatedly, and to fatal effect at the Grande Armée’s supply lines. As David Chandler, an eminent historian of Napoleon’s campaigns, put it: "raids of Cossacks and partisan bands did more harm to the Emperor than all the endeavors of the regular field armies of Holy Russia."

Davydov, who probably inspired Tolstoy’s character "Denisov" in War and Peace, had lobbied his superiors hard for the creation of a small force of behind-the-lines raiders. General Pyotr Bagration, not long before his death in battle at Borodino, gave Davydov permission to launch his swarm — though he detached only a single troop of riders to accompany him. This was all that Davydov needed, though, as he picked up Cossacks, freed Russian soldiers taken prisoner, and recruited willing peasants along the way. Soon the French knew no rest. In Davydov’s own words, they "had no choice but to retreat, preceded and surrounded by partisans."

The Beresina bicentennial provides us a moment to contemplate one of history’s greatest military debacles from an alternative point of view: as an outcome driven not by the clash of hundreds of thousands of troops massed tightly on some constricted battlefield, but rather as the result of constant pinprick attacks from all directions, mounted by a relative handful of irregulars. Who acted like a swarm of bees.

Davydov’s concept of operations portended an entirely different approach to military affairs, one that would grow ever more valuable with the advance of technology. The Russian partisans of 1812 attacked French wagon convoys. Fifty years later, in the Civil War, Confederate raiders disrupted rail lines, imposing near-fatal delays on the advance of Federal forces. In World War I, T.E. Lawrence and his Arab irregulars swarmed the 800-mile-long rail line from Damascus to Medina, contributing mightily to the eventual Turkish collapse. At sea in World War II, U-boat wolf packs swarmed Allied convoys, nearly winning the war for Hitler.

Throughout the Cold War, and on into the post-9/11 era, the swarm — simultaneous attack from several directions — has been the favored fighting method of insurgents and terrorists. The Viet Cong swarmed helicopter landing zones and American foot patrols in Vietnam. Hezbollah did the same to the Israel Defense Forces (IDF) in southern Lebanon during the long war to evict the IDF — and then did so again during the 2006 conflict there. The Free Syrian Army today regularly strikes many places at once, too, giving the Assad regime’s military a problem it cannot solve. Iranian naval strategy embraces swarming as well, the idea being to attack the relatively few, large vessels of the 5th Fleet from all directions with hundreds of small, explosive-laden boats. Even in cyberspace one sees swarms in the form of the millions of hits to single sites, coming from all over the world, that often characterize debilitating "distributed denial-of-service" attacks. If al Qaeda were ever to develop a capacity for sustained swarming in the United States, rather than just mounting rare, one-off attacks, the consequences would be truly dire.

Swarms matter, and have done much to shape the world. As my colleague David Ronfeldt and I have noted in our RAND study of swarms, the phenomenon began long ago. The Mongols were particularly adept at this way of war, following a doctrine they actually named "Crow Swarm." Edward Luttwak, in his masterful The Grand Strategy of the Byzantine Empire, observed that the success of the Byzantines in protecting the edges of empire for nearly a thousand years after the fall of Rome had much to do with their employment of defensive swarm tactics. But Davydov, in a brief campaign launched only after he overcame bureaucratic resistance, helped defeat one of history’s greatest adventurer-conquerors, giving us perhaps the single most dramatic example of swarming ever seen.

Clearly, the insurgents, terrorists, and other irregulars — including "black hat" hackers — who cause most of the world’s mischief today are highly attuned to swarm tactics. In addition to being the bicentennial of Bonaparte’s disaster on the Beresina, today also marks the fourth anniversary of the small terrorist swarm — composed of five two-man teams — that hit Mumbai simultaneously at several different spots and held the city hostage for three days. Nearly 200 were killed, and hundreds more were wounded, as it took days for Indian counter-terrorist forces to mass and move into place to deal with them. Even small swarms are deadly.

Those who must contend with swarms will fail if they rely simply on the heavy hitting of massed forces. Swarms easily slip such punches, and hit back in stinging ways. No, the answer must be to learn to "swarm the swarmers." The Sri Lankan Navy did this against the Tamil Sea Tigers a few years ago, by shifting to a fleet of light, swift vessels that proved even nimbler than those of their enemy. The Sri Lankans quickly proved adept at attacking the Sea Tigers from many directions. And in Gaza, where Hamas leaders think they deterred the Israelis from mounting a ground invasion, the IDF was absolutely ready to move in from several directions simultaneously, reflecting both a refinement of the swarm tactics used the last time they raided Gaza some years ago and the lessons they have learned from Hezbollah.

Denis Davydov’s official report on his operations during the war against Napoleon concluded that his "indestructible swarm" was likely to change the face of war. In fits and starts over the past two centuries, it has begun to do just that. But now the period of fitful progress is over; take warning of the coming swarms that threaten to sweep all before them.