In 1519, Hernán Cortés landed 500 men in 11 ships on the coast of the Yucatan, knowing that he was openly disobeying the governor of Cuba and that he was facing unknown numbers of potential enemies in an unknown situation. Regardless of the moral implications, what happened next was strategically extraordinary: he and his men formed a local alliance, and despite having to beat a desperate retreat on La Noche Triste, they conquered the second largest empire in the New World. As the expeditionary force landed, Cortés made a tactically irrational decision: he scuttled all but one of his ships. In doing so, he hamstrung his own maneuverability, scouting, and communication and supply lines, but he gained one incredible advantage: the complete commitment of his men to the mission, for as Cortés himself said, “If we are going home, we are going in our foes’ ships.” This strategic choice highlights the difference between logic and economists’ concept of “rationality,” in that illogical destruction of one’s own powerful and expensive tools creates a credible commitment that can overcome a serious problem in warfare, that of desertion or cowardice. While Cortés certainly increased the risk to his own life and that of his men, the powerful psychology of being trapped by necessity brought out the very best of the fighting spirit in his men, leading to his dramatic victory.
This episode is certainly not unique in the history of warfare, and was not only enacted by leaders as a method of ensuring commitment, but actually underlay the seemingly crazy (or at least overly risky) cultural practices of several ancient groups. The pervasiveness of these psychological strategies shows that, whether each case was because of a genius decision or an accident of history, they conferred a substantial advantage to their practitioners. (If you are interested in how rational choices are revealed in the history of warfare, please also feel free to read about hostage exchanges and ransoming practices from an earlier blog!) I have collected some of the most interesting examples that I know of, but the following is certainly not an exhaustive list and I encourage other episodes to be mentioned in the comments:
- Julian the Apostate
- Julian the Apostate is most famous for his attempt to reverse Constantine the Great’s Christianization of the Roman Empire, but he was also an ambitious general whose audacity gained him an incredible victory over Germanic invaders against steep odds. He wanted to reverse the stagnation of Roman interests on the Eastern front, where the Sasanian empire had been challenging the Roman army since the mid-3rd century. Having gathered an overwhelming force, he marched to the Euphrates river, took ships from there to the Sasanian capital, while the Sasanians used slash-and-burn tactics to slow his advance. When Julian found the capital (Ctesiphon) undefended, he worried that his men would want to loot the capital and return homeward, continuing the status quo of raiding and retreating. To prevent this, in a move much like that of Cortés, he set fire to his ships and forced his men to press on. In his case, this did not end with stunning victory; Julian overextended his front, was killed, and lost the campaign. Julian’s death shows the very real risks involved in this bold strategy.
- Julius Caesar
- Julian may have taken his cue from a vaunted Roman historical figure. Dramatized perfectly by HBO, the great Roman general and statesman Julius Caesar made huge gamble by taking on the might of the Roman Senate. Despite being heavily outnumbered (over 2 to 1 on foot and as much as 5 to 1 in cavalry), Caesar committed to a decisive battle against his rival Pompey in Greece. While Pompey’s troops had the option of retreating, Caesar relied on the fact that his legionaries had their backs to the Mediterranean, effectively trapping them and giving them no opportunity to rout. While Caesar also tactically out-thought Pompey (he used cunning deployment of reserves to stymie a cavalry charge and break Pompey’s left flank), the key to his victory was that Pompey’s numerically superior force ran first; Pompey met his grisly end shortly thereafter in Egypt, and Caesar went on to gain power over all of Rome.
- The impact of the Teutones on the Roman cultural memory proved so enduring that Teutonic is used today to refer to Germanic peoples, despite the fact that the Teutones themselves were of unknown linguistic origin (they could very well have been Celtic). The Teutones and their allies, the Cimbri, smashed Roman armies which were better trained and equipped multiple times in a row; later Roman authors said they were possessed by the Furor Teutonicus, as they seemed to posses an irrational lack of fear, never fleeing before the enemy. Like many Celtic and Germanic peoples of Northern Europe, the Teutones exhibited a peculiar cultural practice to give an incentive to their men in battle: all of the tribe’s women, children, and supplies were drawn up on wagons behind the men before battles, where the women would take up axes to kill any man who attempted to flee. In doing so, they solved the collective action problem which plagued ancient armies in which a few men running could quickly turn into a rout. If you ran, not only would you die, but your wife and children would as well, and this psychological edge allowed a roving tribe to place the powerful Roman empire in jeopardy for a decade.
- The Persian emperors
- The earliest recorded example of paradoxical risk as a battle custom is the Persian imperial practice of bringing the women, children, and treasure of the emperor and noble families to the war-camp. This seems like a needless and reckless risk, as it would turn a defeat into a disaster in the loss of family and fortune. However, this case is comparable to that of the Teutones, in that it demonstrated the credible commitment of the emperor and nobles to victory, and used this raising of the stakes to incentivize bravery. While the Persians did conquer much of the known world under the nearly mythical leadership of Cyrus the Great, this strategy backfired for the last Achaemenid Persian emperor: when Darius III confronted Alexander the Great at Issus, Alexander’s crack hypaspist troops routed Darius’ flank as well as Darius himself! The imperial family and a great hoard of silver fell into Alexander’s hands, and he would go on to conquer the entirety of the Persian empire.
These examples show the diversity of cultural and personal illustrations of the rational choice theory and psychological warfare that typified some of the most successful military leaders and societies. As the Roman military writer Vegetius stated, “an adversary is more hurt by desertion than slaughter.” Creating unity of purpose is by no means an easy task, and balancing the threat of death by frontline combat with the threat of death during a rout was a problem that plagued leaders from the earliest recorded histories forward (in ancient Greek battles, there were few casualties on the line of battle and the majority of casualties took place during flight from the battlefield. This made the game theoretical choice for each soldier an interesting balance of possibly dying on the line but living if ONLY he ran away, but having a much higher risk of death if a critical mass of troops ran away–perhaps this will be fodder for a future post?). This was a salient and even vital issue for leaders to overcome, and despite the high risks that led to the fall of both Julian and Darius, forcing credible commitment to battle is a fascinating strategy with good historical support for its success. The modern implications of credible commitment problems range from wedding rings to climate accords, but very few modern practices utilize the “illogical rationality” of intentional destruction of secondary options. I continue to wonder what genius, or what society, will come up with a novel application of this concept, and I look forward to seeing the results.
P.S.–thanks to Keith Kallmes for the idea for this article and for helping to write it. Truly, it is his economic background that leads to many of these historical questions about rational choice and human ingenuity in the face of adversity.