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Editor’s Note: This is part of a new series of essays entitled “Battle Studies,” which seeks, through the study of military history, to demonstrate how past lessons about strategy, operations, and tactics apply to current defense challenges.

In 1846, following its annexation of Texas, the United States went to war with Mexico over disputed territory in the Southwest and to enforce its declared southern boundary with Mexico: the Rio Grande. The U.S. president, James K. Polk, had campaigned on a policy platform of territorial expansion and sought to establish the United States as a hemispheric power. Polk coveted California and its natural, deepwater harbors — especially San Francisco.

A command initially assembled to enforce the U.S. southern boundary with Mexico, containing almost the entire professional U.S. Army and led by Maj. Gen. Zachary Taylor, marched south from the Rio Grande to the hills of the Sierra Madre Oriental. Taylor was a seasoned veteran of the War of 1812 and the Second Seminole War, but had never led an army on campaign. He had no experience in war as a senior commander to inform his judgments. The strategic guidance he received dwarfed his available means. His army had remarkable education, experience, and expertise: Four-fifths of its junior officers were trained at the U.S. Military Academy or fought against Seminole Indians in Florida. First ordered to the Rio Grande to defend newly annexed Texas, Taylor’s army transitioned in August to an offensive campaign to defeat Mexico and thereby ensure the final conquest of present-day Arizona, California, Nevada, Utah, Colorado, New Mexico, and Wyoming — all northern Mexico — which other U.S. forces had seized. Despite many difficulties, Taylor’s army succeeded.

The September 1846 Battle of Monterrey, long a hallmark of Zachary Taylor’s northern campaign, was a U.S. victory of strategy, operations, and tactics. Remembered in the historical literature as a deadly foray into urban combat and for its tactical blunders, the battle holds larger implications for the conduct of successful campaigns in war and sound strategy formulation. The inability of Taylor’s campaign to achieve decisive results in a limited, positional war, and the adaptation of American planning that resulted in the 1847 campaign for Mexico City, endure as illuminating examples of how military professionals can employ violent force to make enemies succumb to their will.

A Strategic Trifecta

The treacherous topography, inadequate information on roads in the theater, and lengthy maritime lines of communications made land warfare especially challenging in Mexico. Such challenges required U.S. forces conducting offensive campaigns first to advance across and seize the vast northern periphery of the country, to defeat numerically superior enemy forces in battle, and then to penetrate the interior of the country to capture Mexico City. This approach, which U.S. forces executed in three successive campaigns in 1846 and 1847, accorded with strategic principles ascendant in 19th-century military theory: seize territory as bargaining chips for diplomatic negotiations, defeat armies, and capture capitals.

In 1846, however, it was not obvious to President Polk, Secretary of War William Marcy, and Commanding General of the Army Winfield Scott that defeat of Mexican armies, seizing northern Mexico, and the capture of Mexico City would prove necessary to win the war. Possessing inferior numbers, limited logistics, and with prevalent disease in the low, coastal country, the Americans preferred a limited strategy that entailed defeating Mexican forces and consolidating territorial gains in the northern periphery. The strategy developed in Washington for the war was straightforward: seize deepwater ports on the Pacific Ocean and blockade Mexican coasts, advance into northern Mexico with three independent field forces to occupy Mexican-held territory, and consolidate gains — thereby compelling Mexico to sue for peace.

The Movement to Monterrey

Taylor’s forces numbered some 3,354 regular U.S. Army soldiers when hostilities with Mexico commenced on April 25, 1846. From April to May, Taylor’s army fought a series of battles at Fort Brown, Palo Alto, and Resaca de la Palma before seizing Matamoros and then, in August, extending its advance to Camargo. There it established a base for supplies. Taylor consolidated his forces, as the countryside around Camargo afforded water and wood. Along the Gulf of Mexico coast, Point Isabel connected the logistical tail of Taylor’s army to the sea, where Americans received supplies transported by ocean-faring vessels. From Point Isabel, lighters and steamers ferried supply upriver. The route along both banks of the Rio Grande proved useful for moving wagons and artillery.

More than engaging in battles that lacked strategic purpose, Taylor moved his army along the Rio Grande and to the hills of the Sierra Madre in a manner that reflected a clear design. Taylor sought first to control the line of the Rio Grande, and then the major north to south road from Monterrey that ran from the foothills of the Sierra Madre through Saltillo and Buena Vista to San Luis Potosí, and onward to Mexico City. His movement from Point Isabel to Camargo reflected a sound instinct to move river-borne supply along the Rio Grande by steamers, while using the shortest possible overland route to move his army with whatever mules or wagons he could obtain. From Camargo, Taylor could move on Monterrey, the capital of Nueva Leon, and from there continue his campaign farther into the country’s interior. To stage supplies, Taylor displayed considerable initiative given the poor state of the existing logistical system: Unwilling to wait on the fiscally constrained and glacial wartime procurement processes of the Quartermaster’s Department, for instance, he dispatched agents from Mexico throughout the United States — by way of New Orleans to Louisville and Pittsburgh — to secure watercraft. Although he anticipated many logistical requirements involved, and made timely requisitions, Taylor struggled to secure rapid transport for his army. After ordering one division forward to establish an intermediate base at Cerralvo, Taylor marched his army toward Monterrey. Through effective employment of forward cavalry actions that secured their movements and provided intelligence, Taylor’s army arrived at Walnut Springs on Sept. 19 and bivouacked three miles from Monterrey.

Mexican Gibraltar

Monterrey rose 1,626 feet above sea level, teemed with defenders — approximately 7,300 men and 42 guns under the command of Mexican Gen. Pedro de Ampudia — and presented a difficult tactical dilemma. Nestled on a plain among the high foothills and ridges of the Sierra Madre, the city lay in a bend of the Rio Santa Catarina and was flanked by fortifications along its northern and westward approaches. To the north lay an extensive plain, dominated by a fortress — the “Black Fort” — with guns that commanded the surrounding terrain. To capture the city, Taylor needed to isolate Monterrey by controlling the roads that led to it, cut off its communications, reduce its formidable defenses, and advance into the center plaza, which a young Lt. Ulysses S. Grant identified as its “citadel.” Taylor’s engineers marked key terrain, reconnoitered routes of attack for the infantry, and placed artillery.

On the eve of battle — Sept. 20 — Taylor’s command, augmented by volunteers, consisted of 6,500 men organized into three divisions. His plan of battle suited the tactical problem. One division of army regulars — the main effort — would advance against the Saltillo Road, the western approach that ran through a critical mountain pass to Saltillo, thus blocking any advance of enemy forces from the south and west. This would sever Monterrey from military supplies and allow the Americans to envelop the city. Possession of the Saltillo Road and two key terrain features west and south of town — Independence and Federation hills — would also give the Americans a route of ingress into Monterrey. In the center, siege artillery would reduce the Black Fort. Two divisions, one of regulars and another of volunteers, would advance on enemy positions from the north and east, capture Mexican defensive works, divert and fix enemy forces, and, if possible, enter the city. These attacks would thus support the main effort, the enveloping attack, on the western edge of Monterrey.

American forces endured hard fighting on Sept. 21-23. Napoleon Jackson Tecumseh Dana, an infantry lieutenant commissioned from the U.S. Military Academy in the Class of 1842, described Monterrey as “a second West Point” and noted “the immense strength” of the city, and with “what military judgment it had been fortified by the enemy.” It was, he remarked, “a perfect Gibraltar.” American commanders pressed their attacks against this Gibraltar with mixed results. Upon the heights to the west and south, U.S. regulars and Texas Rangers found quicker success and suffered fewer casualties. To the east, gains were slow and casualties heavy. Riding forward to join the 4th Infantry Regiment in its attack against Mexican defenses on the eastern edge of the town, Grant witnessed one-third of his regiment fall in minutes. He lamented the poor tactical planning, or execution, at the brigade level. From the northern and eastern approaches into the city, Americans confronted adobe houses thick with defenders firing from portals and rooftops. The Americans stood and fought in the streets, suffering greatly. One battery of light field artillery, led by Capt. Braxton Bragg, with Lts. Samuel French and John Reynolds commanding guns, “penetrated … some distance into the city,” but lost numerous horses. Nevertheless, the Americans pressed their advance and “took one work after another, until they were in possession of all except the citadel.” Fighting to the plaza from the west, U.S. forces, noting the heavy casualties suffered by their counterparts the day before in frontal street attacks on the eastern side of town, blew holes through buildings and burrowed their way through Monterrey. On the evening of the 23rd, American siege artillery lobbed explosive rounds into the plaza. Shells “burst beautifully … scattering death and devastation on all sides.” The next day, Mexican forces surrendered.

Image: Mexican War: Taylor’s Campaign, 1846-1847 (West Point, N.Y.: Dept. of Military Art and Engineering, United States Military Academy, 1956).

Analysis and Impacts

How did U.S. forces perform on campaign? Contra longstanding criticisms of amateurism and tactical floundering that permeate the historiography, Taylor methodically directed tactical actions and military resources toward accomplishing ambitious policy objectives. The strategic guidance Taylor received, obliging him first to defend Texas and then conduct offensive operations, imposed unique demands on the commander. In the theater, Taylor grasped a purposeful plan of campaign and sought to execute that plan. Like Scott in Washington, Taylor correctly perceived the significance of Monterrey for supplying an army, extending operational reach, maintaining flexible combat power, and protecting his army. Taylor “pushed the campaign as hard and as fast and as far as the means at his command would permit.” At Monterrey, his plan of battle was suitable, although coordination suffered and cohesion in the attack dissipated. In the end, despite suboptimal small-unit tactical coordination, U.S. forces had enough firepower and proficiency to win a battle over difficult terrain with imperfect information and intelligence.

The capture of Monterrey proved indecisive and forced an American strategic reassessment. Upon reaching Saltillo with his army in November, Taylor advised the administration in Washington and his commander that advancing to Mexico City from Saltillo and by the overland route brought inordinate and unacceptable risk: His position would prove too difficult, his line of operations too long, and he lacked the means to maintain the fighting strength of his army into the interior, a distance of more than 300 miles across the high desert. Taylor wisely counseled a campaign to capture Mexico City from a base of operations on the Gulf coast, and, after Buena Vista, kept his army at Monterrey, where it could benefit from a favorable climate and an abundance of food and fresh water.

Although indecisive, Taylor’s northern Mexico campaign reflected important developments. First, without timely communication, with meager supply, and far from American cities, Taylor won a string of battles that inspired great confidence in his men and fired the public imagination. These successes ultimately catapulted Taylor to the presidency. Second, events in northern Mexico, with Taylor’s urging, compelled the U.S. government to modify its approach to war, grow the U.S. Army, and increase the procurement of supplies for prosecuting the war. Taylor’s campaign thus proved an inflection point for the national development of logistics and supply for expeditionary joint operations. Third, victory at Monterrey revealed that the United States needed a more decisive victory over Mexico to force its surrender. A small war in a remote part of the country was insufficient: Defeat of the enemy would only result from occupying its capital. This required a swift campaign targeted at the heart of Mexico without interruptions of offensive operations. Strategic re-orientation compelled significant changes in the theater of war and convinced the Americans to undertake a new campaign in a different area of operations with a shorter logistics tail. In November 1846, Gen. Scott departed Washington to command the amphibious assault and invasion at Veracruz.

At the level of tactics, the U.S. victory demonstrated the value of highly mobile field artillery, a pre-war innovation. Though in Mexico gunners sometimes fought as infantry, still the employment of the nascent American light artillery offered lessons for study. Writing near the turn of the 20th century in the Journal of the Military Service Institution of the United States, a leading venue for professional thought of the era, one officer noted that the self-sufficiency and battlefield supremacy of artillery in modern warfare were lessons derived not from rapid-firing breechloaders on battlefields of the Franco-Prussian War, but from Monterrey and Buena Vista. In the war, wrote Lt. G.W. Van Deusen, “especially during Taylor’s campaigns, the artillery seemed almost invincible, and, by its practically unaided efforts, turned the tide of battle, and gained the day for our troops.” Fighting at Monterrey and beyond showcased the “high state of efficiency” of U.S. soldiers. An artillerist wrote in the inaugural 1892 issue of the Journal of the United States Artillery, echoing the theme, “though the armies were small, the service peculiar, [and] the operations as nothing compared to those of later days, yet the spirit was there, and for the first time in our history the field artillery came prominently forth as an indispensable fighting force.” He continued, “here perhaps first of all upon this continent the light artillery proved … that its own fire, even at short range was enough for its own preservation, and enough to defeat the attack and save the day.”

The Lessons of Monterrey

For good reason, U.S. Army professionals remember Monterrey as their first urban battle. But interpretations of Monterrey and its significance for urban operations in American warfare require tempering. Soldiers at Monterrey regarded the battle as intense, but their successors in the profession seldom noted the significance of the battle for the evolution of infantry doctrine or the conduct of urban warfare. Unsurprisingly, the June 1944 iteration of Field Manual 100-5, Operations, drew no historical vignettes from Monterrey, but in detailing attacks on towns and villages, prescribed tactics — including fixing the enemy with one force and enveloping with another — that endure in current doctrine and hearken to Taylor’s approach.

Of course, technological differences distinguish the fighting at Monterrey from modern warfare. Field artillery in 1846 lacked the firepower to demolish buildings. Despite advantages for defenders that came with fighting from houses and parapeted rooftops, initiative lay with the attacker who, if girded by sufficient numbers and superior discipline at the point of attack, and pressed the attack vigorously, could overwhelm defensive positions with the bayonet faster than defenders could aim, fire, and reload smoothbore muskets. Not until advances in rapid-fire small arms and machine guns would modern cities transform into mini-fortresses with groups of buildings, in depth, functioning as “mutually supporting defensive networks,” and become obstacles to armored vehicles, negating benefits of mobility and maneuver, and affording firepower advantages to defenders. Combat in European villages compelled the U.S. Army in January 1944 to issue Field Manual 31-50, Attack on a Fortified Position and Combat in Towns, which directed rifle squads to avoid streets and burrow through buildings and from house to house — lasting lessons of Monterrey, but evidence, more contemporaneously, of 20th-century European warfare.

Nonetheless, the American experience in northern Mexico offers useful lessons. First, the United States has an historical tendency of crafting foreign policy to secure its proximate grand strategic interests. This includes conducting offensive joint campaigns to enhance the material power of the nation. In the future, civilian leadership may order U.S. forces to do so again.

Second, the examples of Zachary Taylor and Winfield Scott suggest that strategy and campaign design need refinement to their purest elements. Strategy entails clear thinking about how the nation, but especially the armed forces, “intend to prevail in a theater of war.” The successful prosecution of Taylor’s campaign, its culmination, and the skillful conceptualization, planning, and execution of Scott’s 1847 campaign, conjures up an older and more instructive definition of operational art in U.S. Army doctrine: “the pursuit of strategic objectives … through the arrangement of tactical actions in time, space, and purpose.” The clarity and simplicity of strategy formulation and campaign design in Mexico should evoke admiration and inspire emulation.

Finally, in the future, as in 1846 when Americans fought outnumbered far from the United States, superior discipline and tactical proficiency will likely prove critical. This superiority should have its origins in education and training before hostilities begin. In higher considerations of strategy, military professionals must never take fundamental proficiencies for granted, and it should be said of Americans in future wars, as General of the Armies U.S. Grant wrote of the soldiers who fought with Gen. Taylor, “the men engaged in the Mexican war were brave, and the officers of the regular army, from highest to lowest, were educated in their profession. A more efficient army for its number and armament, I do not believe ever fought a battle …”

Mitchell G. Klingenberg, Ph.D., is an assistant professor in the Department of Military History at the U.S. Army Command and General Staff College. He is the author of “When Americans Marched to Mexico City.”

The author thanks Thomas Bruscino and Wayne Wei-siang Hsieh for reading this article and for their helpful comments. The views expressed in this article are the author’s alone and do not reflect the positions of any U.S. government entity.

Image: Tompkins Harrison Matteson via Wikimedia Commons