The Birth of American Operational Art: Winfield Scott’s Mexico City Campaign during the Mexican-American War of 1846-1848

General Winfield Scott’s campaign against Mexico City in 1847 constitutes one of the earliest examples of American operational art. [1] Scott’s performance as a commander during the campaign stands out as a unique example to study for contemporary operational artists. Indeed, Scott’s calm and continued focus on the strategic objective combined with self-confidence, a deep understanding of his opponent’s social, military, and economic situation, and operational and tactical patience enabled the U.S. force to achieve its strategic objective despite being outnumbered in a hostile environment. Scott skillfully balanced risk and opportunity in an overall operational approach along three lines of effort, to achieve the strategic objective by arranging a series of related major operations in time, space, and purpose.[2] Furthermore, the operation is an example of the impact political and civilian considerations on both sides of a conflict can have on military operations.[3]

In 1844, James K. Polk (D) ran for president based on a territorial expansionism agenda.[4] Elected, Polk began deliberate efforts to expand the U.S. territories westwards. Specifically, the President regarded the independent republic of Texas, and the Mexican territories of New Mexico, and California as a natural part of the U.S. At the outbreak of the Mexican – American War, Polk’s strategy was to defend Texas along the Rio Grande, invade and hold territories in northern Mexico, and force the Mexican government into peace negotiations. A quick and cheap end to the war was imperative, as the war was unpopular with the opposition and the public in general.[5] The strategy, however, did not consider domestic Mexican socio-economic factors. The territories occupied only comprised some 7% of the Mexican population and no vital economic assets. Therefore, the pressure on the Mexicans was not substantial enough to coerce the Mexican government into favorable peace negotiations.

General Zachary Taylor, the officer responsible for the campaign in Northern Mexico, soon found himself in a stalemate situation unable to accomplish the strategic objectives with the resources available to him. Taylor’s situation let Scott to formulate the problem, the Northern Mexico campaign epitomized: “If you come with few, we will overwhelm you; if with many, you will overwhelm yourself.”[6] The lack of results in Northern Mexico prompted Scott to plan a campaign that would open a new front in the war. Scott realized that he was to threaten the Mexican government directly by force before it would sue for peace. That meant either capturing or threatening Mexico City.[7] Taylor already attempted a northern approach. Thus, Scott suggested an approach from the Mexican Gulf coast followed by an inland march on Mexico City (figure 2).[8] The only place suited for such an approach was Vera Cruz.[9] In contrast to Taylor’s northern approach, Scott’s invasion via Veracruz to Mexico City would affect more than half of Mexico’s population and vital socio-economic infrastructures.[10] Convinced of the quality and positive prospects of the plan, Polk, reluctantly though, appointed Scott to lead the campaign.[11] Scott, now in charge of a politically charged campaign, had to balance operational and tactical difficulties on the battlefield as well as political considerations in Washington. To make matters worse, internal politics and rivalry between several officers, most noteworthy the division commanders, would persist and evolve to the worse throughout the campaign.[12]

In the early nineteenth century, the young post-colonial Mexican state was by no means a unified and cohesive state.[13] After winning independence, the new Mexican rulers largely kept the colonial institutional structure intact. Hence, the new rulers, primarily criollos of European desent, also kept a vast majority of the Mexican people, primarily the decedents from the pre-colonial liberal Mexicans out of political influence.[14] In addition, the conservative criollos took away titles of land and access to legal measures regarding land disputes from the liberals.[15] For the vast majority of the original Mexicans, religion, culture, and family tied their entire identity to the land they owned. As a result, internal violence and rebellions directed at the Mexican authorities were frequent from the 1820s until the 1910-1921 Mexican Civil War. Ultimately, the Mexican elite were more concerned with the domestic threat posed by local guerillas, than with the U.S. invaders.[16] Consequently, the Mexican government and the Mexican army under Santa Anna fought a widespread counterinsurgency campaign alongside countering the outside invasion. At no point was a feeling of national pride or cohesion established among the Mexican people. Consequently, many Mexicans actively worked with the Americans as it suited their own, local interests the best.[17]

In planning the campaign Scott, a profound strategic and operational planner, considered a host of variables involved, besides the political and economic mentioned above.[18] In the military calculations, Scott assumed that the Mexican government, with its forces divided between the northern border, the counterinsurgency missions, and the protection of fixed locations such as Mexico City, would be able to meet the U.S. forces with about 30.000 regular Army troops.[19] Scott on his own part, calculated 10-12.000 troops, including 2.000 cavalry and 600 artillery troops, would be necessary to land at Vera Cruz and capture the city and the near-by fortified castle of San Juan d’Ulloa. Hence, to march upon Mexico City, gather supplies along the route, and protect the lines of communications back to Vera Cruz, up to 20.000 troops would be necessary. The troop levels never reached the anticipated level, which eventually forced Scott to sever his lines of communications. In addition, Scott also had to protect the force from the local Mexican population. A positive population would likely let the U.S. forces forage of the lands by contract. Conversely, a hostile population could defeat the U.S. force by sheer numbers through guerilla warfare and attrition. Scott addressed this risk throughout the campaign. In fact, Scott utilized his knowledge about the internal situation in Mexico to turn risk into advantage by making sure that the U.S. forces treated the civilian population with dignity and respect. He enforced martial law and punished any assault on the civilian population by U.S. soldiers. In addition, the U.S. forces paid for supplies retrieved locally, and respected the local culture and religion.[20] With the strategic objective and the operational environment in mind, Scott’s problem, then, was how he would coerce the Mexican government into favorable peace terms, in a delicate political situation, facing a numerical superior Mexican Army in a potentially hostile environment while supplying and preserving his force.

Having considered the overall objective, the problem, the operational environment, and relevant variables, Scott was able to outline his plan. The operational approach consisted of a continued pressure against the Mexican government until it felt compelled to sue for peace. The end state was a peace treaty established with Mexican government conceding Texas, New Mexico, and California to the U.S., and the Army disengaged and redeployed to the United States. Scott could achieve the end state at any point during the campaign. The destruction of the Mexican Army or the capture of Mexico City was in and of itself not an objective, but merely a way to meet the objective. Consequently, the campaign was of a limited objective. During the campaign, Scott paused after each engagement to allow the Mexican government time to sue for peace. Scott’s soldiers labeled the approach “the Sword and the Olive Branch”.

Scott conducted the campaign along three Lines of Effort (LoE):[21] (1) Defeat the Mexican Army while marching on Mexico City. The purpose of this LoE was to increase the pressure on the Mexican government by a combination of tactical battles and the physical approach to Mexico City.[22] (2) Sustain the force. This LoE provided the Army with food supplies, ammunition, reinforcements, and money with as few resources as possible. Money was an important part of Scott’s design as it enabled him to purchase supplies from the local Mexicans thus spending less combat power on keeping LoCs open and sending logistic convoys back and forth between the Army and the logistic bases. Initially, Scott employed a combination of local purchase and resupply from Vera Cruz. As the LoC grew longer and the guerilla attacks increased in frequency and size, tough, Scott gave up protecting the LoC and relied increasingly on what supplies he could purchase locally. (3) Protect the force. This LoE intended to protect the Army’s combat power in several different ways. First, Scott was painfully aware of the seasonal impact on the level of diseases along the Mexican coast. Consequently, he moved as much of the force away from the coast as soon as possible after taking Vera Cruz. Secondly, Scott sought to decrease the friction on the Army by pacifying the civilian population along the route from Vera Crus to Mexico City.[23] Scott put the U.S. soldiers under strict disciplinary measures in order not to harm, provoke, and upset the local population.[24] Only partially successful in constraining the U.S. soldiers, particularly the volunteer regiments, the size and ferocity of local guerilla forces could be attributed directly to the level of U.S. assaults against local Mexicans in any given area.[25] Because of the guerilla up rise, Scott issued additional instructions to the Army to prevent guerillas from killing or capturing U.S. soldiers. Soldiers were to stay in the camps and only move around on official business, armed and in groups. Eventually, Scott’s aim was to keep the civilian population out of the war, as he knew from studying the Spanish insurrection against Napoleon that a hostile population could virtually defeat an invading Army.[26]

In addition to protecting the Army from the environment and the local population, Scott realized that excessive loses in combat could not be replaced and such loses eventually could prevent him from compelling the Mexican government to yield to U.S. demands. Consequently, he carefully balanced and applied the elements of combat power at each battle to preserve the Army’s strength.[27]

At Cerro Gordo, the first battle after leaving Vera Cruz, Scott spent full five days in preparations for the attack on well-prepared Mexican positions.[28] He emphasized thorough reconnaissance of the Mexican positions to gather the best possible intelligence prior to planning the attack. The plan of attack stressed a Napoleonic-style deception force to fix the front of the Mexican position while the bulk of the U.S. force marched around the Mexicans, turned the Mexican flank, and cut off the rear.[29] The attack, though, did not come as a complete surprise, as Brigadier General David E. Twiggs neglected to fully cover his flanking march. The Mexicans stopped the initial attack, but that led the Mexicans to believe the flank was strong enough to withstand U.S. attacks.[30] Resuming the flanking attack the next morning, Scott had issued new orders, and the U.S. forces coordinated and synchronized movement and maneuver with artillery fire at the Mexican flank. The U.S. Army soon drove off the Mexicans and despite a poor performance by the U.S. force holding the Mexican front, Scott’s Army only took minor casualties. [31] The thorough planning and preparation of the battle of Cerro Gordo showed Scott and the rest of the U.S. forces how the careful application of intelligence, movement and maneuver, and fire support tied together by precise mission orders and executed under brave leadership could achieve the victory while, to the fullest possible extent, protecting and preserving the force. Furthermore, Scott had accomplished the exact purpose he envisioned for the battles between Vera Cruz and Mexico City: to increase the military and political pressure on the Mexican Government.[32] Unfortunately, Cerro Gordo also caused the interim Mexican president to create the light corps of guerilla warriors to wage unconventional warfare against the U.S. invaders.[33]

After the battle, Scott dealt with issues such as Mexican prisoners, captured Mexican weapons, and materiel. Again, to preserve his force for combat, he did not retain the Mexicans as prisoners, nor did he attempt to keep all the captured weapons. The focus after Cerro Gordo was still protection of the force:  to reconstitute and move decisively away from the coast and the yellow fever towards Jalapa and beyond. In Jalapa, Scott rebuild supplies, attended the wounded, successfully continued his pacification efforts among the local population, and sustained the influence campaign designed to drive a wedge between the Mexican population and its government.[34]

Four more battles occurred prior to Scott’s occupation of Mexico City on September 15, 1847 (figure 3).[35] The battles of Contreras and Churubusco (August 20, 1847), Molino del Rey (September 8, 1847), Chapultepec (September 13, 1847), and Mexico City itself (September 13-15, 1847). All of the battles illustrated analogous attributes as in the battles of Vera Cruz and Cerro Gordo. At Contreras, Twiggs’ division surprised and surrounded General Valencia’s command in a pre-dawn fix and flank Napoleonic maneuver. At Churubusco, Brigadier General William Worth’s division turned the defending Mexican force to achieve a favorable force ratio.[36] The battle came more or less as a surprise for the Mexicans, as Scott’s Army traveled a long way through almost impassable terrain to attack, as opposed to taking a more direct route to Mexico City. Again, by thorough reconnaissance and intelligence gathering, deliberate work by engineers, operational patience, and leadership Scott protected his combat power and sought the most favorable force ration for the inevitable battles with Santa Anna’s forces. Again, concerned with preserving combat power, Scott halted his forces to reorganize and deliberately plan the next stage instead of pursuing the dispirited and fleeing Mexicans into Mexico City.[37] The comparable loses of the two engagements illustrates the effectiveness of Scott’s approach; Scott lost 1.5% of his force killed in action and 10.5% wounded in action, whereas Santa Anna lost almost 33% of his entire force.[38] At Molino del Rey Scott, uncharacteristically, left the planning of the attack to Worth. The lack of reconnaissance and intelligence gathering prior to the attack let to the highest casualties of any single battle during the campaign. The head on assault was initially repelled by an undetected Mexican artillery position and only after having received reinforcements did Worth’s division take the objective. Had a similar approach been the blueprint of every attack during the campaign, the overall loses would very likely have prevented Scott from achieving the campaign objectives.

The application of the intelligence element of combat power at all levels deserves special attention. Not only did Scott put premier emphasis on gathering solid information on the terrain and intelligence on the enemy’s disposition and strength. Scott also used strategic intelligence gathered by civilian agents sent to Mexico City by the U.S. government. Scott utilized the same agents in his influence campaign. Among remarkable results, the agents persuaded the Mexican church not to engage in active resistance against the Americans. With a heavy influence on the local population, the church could potentially have been a factor uniting the Mexicans against Scott’s army. The same agents provided Scott with a good impression for the support for the Mexican government, and indicator of the degree of success of his pacification and strategic communication efforts.

In judging Scott’s application of the elements of combat power, as defined in today’s doctrine, it is clear that a very deliberate, patient, and thorough overall plan to protect and sustain the force drove the preponderance of Scott’s decisions. As such, the application of movement and maneuver, intelligence, and fires supported that effort in a measured attempt always to secure surprise and favorable force ratio when possible. This approach was not as self-evident in nineteenth century application of military forces, as it is in the dawn of the twenty-first century. In addition, in judging the overall campaign and individual battles, it seems just to credit Scott’s strategic, operational, and tactical understanding of the situation in both camps along with his efforts to visualize and describe his vision to commanders, soldiers, and local Mexicans alike, with the ultimate success of the campaign. Similarly, Scott succeeded in carefully directing tactical as well as operational actions while constantly accessing the effect his Army’s operations had on both the enemy forces and the local population. Despite Scott’s personal flaws, he succeeded in leading a comparably small force, deep into hostile territory, and achieve the strategic objectives defined by the U.S. government. [39]

When a military professional conduct an analysis of a historical campaign, it is instructive to view the commander’s planning and execution of the campaign according to today’s doctrine and theory. It is also, however, useful to study what contemporary examples and theorists informed the commander’s decisions. Scott was a well-read and experienced commander. His studies of military theorists such as Thucydides, Machiavelli, Napoleon, and Jomini, informed his actions.[40] Jomini’s account of Napoleon’s campaign against Moscow, among other things, taught Scott how a force, which keep long LoCs open to a distant base of supply, slowly gets depleted by the requirement to keep the LoCs open. Similarly, Napoleon’s conquest of the Iberian Peninsula and the subsequent Spanish insurrection especially informed Scott of the risk of a national war, and that “a fanatical people may arm under the appeal of its priests.”[41] Even in operational and tactical matters, such as choosing the landing site, the inland lines of operation, bases, plans of march and attack, and approach to Mexico City Scott sought inspiration in Jomini[42]. Finally, Scott, on more than one occasion, displayed what both the Enlightenment school of thought, represented by Jomini, and the subsequent German movement emphasized; that not all battles are planned, thus a superior general’s coup d’oeil often is required to carry the day.[43] It is no surprise, then, that Jomini himself classified Scott’s campaign as brilliant.[44]

In The Landmark Thucydides: A Comprehensive Guide to the Peloponnesian War, Thucydides describes how fear, honor, and interest are at the core of human nature and state motivation.[45] Fear, honor, and interest clearly shaped Scott’s Mexico City Campaign. The overall reason for the war was American interests, the Manifest Destiny.[46] Inside Scott’s army, fear, honor, and personal interest prompted many internal disputes. Some generals wanted personal glory; others had political affiliations and ambitions, which guided their actions. Scott himself was afraid of lower ranking officers taking the spotlight in important battles. On the Mexican side, internal disputes, fear of the population as well as the U.S. invaders drove much of the internal political actions and decisions. Personal interests was the foremost motivation for the majority of the Mexicans, including Santa Anna himself who profited by the American invasion by selling beef from one of his estates near Jalapa.[47] Similarly, personal interest prevented Mexican commanders such as Juan Álvarez from fully engaging in the defense of Mexico City to preserve their forces for a post-war internal power struggle.[48]

Even though Scott did not have the opportunity to study Clausewitz’s Trinity, the concept illustrates Scott’s accomplishment. [49] By his military actions and simultaneous pacification efforts, Scott effectively drove a wedge between the Mexican government and its people preventing the primordial violence and enmity from devouring the small American force. Doing so, Scott successfully isolated the three elements in Clausewitz’s Trinity, which, to most effectively wage a national war, must be in a balanced concert. Similarly, Scott’s handling of Clausewitzian concepts such as chance, uncertainty, and friction was evident throughout the campaign. Indeed, Scott epitomized what the German aufklareres in general came to recognize; that the military profession could be studied theoretically, and that a broad general education is necessary for developing officers’ personality.[50]

Many aspects of Scott’s Mexico City campaign are worth a study for the contemporary military practitioner. The most striking, though, are how Scott balanced risk and opportunity through a combination of careful planning and preparation, combined with strategic and operational understanding and patience, Scott’s tactical skill, and steadfast leadership throughout the campaign.