Reconnaissance Pull in the Offense: A Mexican-American War Case Study

Fall 2019 Reconnaissance Pull in the Offense: a Mexican-American War Case Study by MAJ Nathan A. Jennings Reconnaissance by cavalry formations is a critical enabling function for bri gades and divisions executing decisive action in unified land operations. Doc trinally defined as a proactive action to collect information about threats, in frastructure, terrain, weather and so ciety, the forward action is typically di vided into two techniques: pull and push. While the former, according to Field Manual (FM) 3-98, Reconnais sance and Security Operations, gains “an understanding of enemy weak nesses” to “pull the main body to po sitions of tactical advantage,” the lat ter is employed when commanders have a “thorough understanding of the operational environment” and “push reconnaissance assets” into “areas of operation to confirm, deny and vali date planning assumptions.”1 Though it remains important for caval ry formations to master both tech niques, cursory assessment of Ameri can conflicts since the onset of mech anization reveals that scouts are pushed during offensive campaigns far more often than they meaningfully pull their higher echelon. World War II, the Persian Gulf War and Operation Iraqi Freedom, for example, all featured reg iments and squadrons that were com pelled to adopt rapid and forceful in formation collection based on opera tional and political demands placed on their higher headquarters’ tempo. In this context, the aim by most cavalry units to conduct deliberate and stealthy movement is historically unre alistic; ground reconnaissance actions in future conflicts will likely remain ac celerated and aggressive to inform ad vanced-stage planning and execution. Monterrey campaign One instructive example of reconnais sance pull, however, can be found in the 19th Century, when the U.S. Army invaded northern Mexico during the Mexican-American War. In that con flict, a small expeditionary force of 3,550 Soldiers under future U.S. Presi dent GEN Zachary Taylor crossed the Rio Grande, defeated larger Mexican armies and captured the provincial capital of Monterrey to secure Ameri can control of Texas. Throughout his advance – which required Figure 1. CPT Charles A. May’s squadron of 2nd Dragoons (now 2nd Cavalry Regiment) slashes through enemy lines in an attack at Resaca de la Palma, TX, May 9, 1846, a battle that climaxed the opening campaigns of the Mexican-American War. The cavalry squadron’s bravery proved that the 2,500 American soldiers under GEN Zachary Taylor had enough self-confidence and pluck to shatter the Mexican force of 6,000 and eject it forever from Texas. Thereafter throughout the war, the U.S. Army never lacked daring. May’s attack order was simple and effective: “Remember your regiment and follow your officers.” (U.S. Army in Action Series; painting commissioned by the U.S. Army and in the public domain)

Fall 2019 maneuvering deep into unfamiliar and hostile territory – the general relied on volunteer cavalry in the form of feder alized Texas Rangers to constantly in form his movement. These scouts ef fectively fulfilled the modern Army’s imperative for reconnaissance units to “enable all units to seize, retain and ex ploit the initiative across the range of military operations.” The requirement for Lone Star scouts in the Monterrey Campaign, which lasted from April to September 1846, began with Taylor’s initial offensive along the Rio Grande. As veterans of the Wars of the Texas Republic, the Lone Star scouts’ expertise in mounted warfare proved critical as the American expedition marched into unfamiliar terrain and grappled with the much larger Mexican army. The volunteers’ contributions during the forcible entry reflected traditional functions of light cavalry in the post-Napoleonic era as they explored far ahead of the infantry and artillery columns to identify traf ficable routes, deflect opposing scouts and report enemy presence. Their fa miliarity with desert navigation and Mexican culture, in addition to their native horses’ acclimatized endurance, allowed them to patrol farther than the unprepared U.S. dragoons. This type of wartime augmentation by locally recruited partisans held a com monplace role in 19th Century warfare. Known alternately as irregular or aux iliary cavalry, the Texas Rangers’ ama teur status reflected their informal tra dition and temporary activation in con trast with the professionalism and per manency of the branches of most na tion-state armies. Similar to allied In dians serving the U.S. Army, Russian Cossacks in Europe or the Silladar Na tive Horsemen of British India at that time, Texas volunteers supplanted the American regulars’ mobility deficiency with region-specific skills.2 A former Texas Ranger named Samuel Walker, originally from Maryland, or ganized and led the first scout compa ny to ride south. After beginning active service with an inauspicious start when a Mexican patrol overran their forward camp April 28, Walker and his volun teers gained national fame when they re-established communications be tween the American main army at Port Isabel and a forward infantry outpost on the Rio Grande. The act required the Texans to break through a substan tial Mexican screen, which had stymied Taylor’s remaining dragoons, to make contact with the isolated battalion. Ab ner Doubleday, a U.S. artillery officer with the army, praised the “gallant” Walker in his journal, noting that “in spite of the dangers and obstacles he succeeded in executing his daring proj ect.”3 On May 7, 1846, the war moved be yond skirmishing and into main-force combat when Taylor decisively defeat ed the Mexican Army of the North at the Battle of Palo Alto and followed with another bloody victory at Resaca de la Palma the next day. The general accomplished these feats through in novative positioning of “flying artil lery,” or mobile light cannon, along the frontlines that enabled it to fire direct ly into the opposing infantry ranks. LT Napoleon Dana, 7th U.S. Infantry Regi ment, called the victory “a horrid spec tacle” and “remarkable and brilliant,” while noting that “grape and canister shot had literally mowed them down.”4 Texas scouts resumed reconnaissance duty as the shattered Mexican army re treated south. Reconnaissance pull into Mexico Taylor elected to build on his battle field success with a deeper invasion of Mexico to solidify American control of Texas and compel territorial conces sions. However, he and his command ers had little intelligence concerning routes and enemy disposition to their front. To inform his planning, the gen eral dispatched a combined force of dragoons and Texans May 19 to locate the Mexican retrograde. This force in cluded a newly arrived volunteer com pany led by another former Ranger, CPT John Price. CPT William Henry of 3rd U.S. Infantry Regiment recalled how the riders followed the retreating en emy for almost 60 miles and then “fell in with the rearguard of the army and attacked them.” The task force suffered two wounded in the skirmish and sub sequently reported the enemy position to Taylor.5 Events continued to develop south of the Rio Grande, while the newly annexed state of Texas mobilized two full mounted rifles regiments of 10 companies each, numbered 1st and 2nd respectively, to address Taylor’s mobil ity requirement. The general had be gun his advance west from Matamoros throughout the first and second weeks of June, and a third company of Texas scouts, under famed frontier fighter CPT Ben McCulloch, joined the army May 23. He joined the others in a field camp that Samuel Reid, a scout from Louisiana in McCulloch’s company, compared to “a Hottentot hamlet” and an “Indian village.” On June 5, Taylor dispatched Price’s men to provide route security for 1st U.S. Infantry Reg iment’s march to the town of Reynosa 60 miles up the Rio Grande.6 On June 12, the Texans began concert ed forward patrols to inform and “pull” the Army’s columns into unfamiliar ter ritory. McCulloch’s company, in partic ular, rode southeast toward Linares to, as reported by Reid, “gain information touching the number and disposition of the enemy.” They also hoped to as certain if a passable southern ap proach to Monterrey existed to sup port “the line of march for a large divi sion, with its artillery and wagons.” Aware of possible observation by “Mexican spies,” the scouts feinted to ward Reynosa and then cut cross-coun try to the Linares Road after nightfall. After finding that direction impassable for the expedition’s logistical and artil lery trains, they returned to report findings and established a temporary camp with 1st U.S. Infantry at Reynosa.7 The Texans’ region-specific capabilities made them uniquely suited to shape Taylor’s scheme of maneuver through out the invasion. In one instance, which revealed the advantage of pre vious border experience during the Texas Republic’s many wars against Mexico, McCulloch’s reconnaissance party leveraged cultural familiarity against an enemy patrol. The Ranger captain first deceived the enemy by hailing them in Spanish before opening fire and capturing a mail carrier. He then translated a captured map and questioned local civilians, which yield ed intelligence on the dearth of water and forage ahead. This conversancy in the Spanish language represented an other of the Texans’ unique skills.8

Fall 2019 Forward and proactive information col lection by mobile scouts, so critically needed to maneuver cumbersome 19th Century infantry and artillery regi ments through foreign landscapes, made the Lone Star auxiliaries an indis pensable asset during the American advance into Mexico. Taylor himself later reported of McCulloch that “his valuable services as a partisan and spy were greatly needed.” He went on – in language uncharacteristically generous for a Regular Army officer speaking of disdained volunteers – to note that “the services rendered by MAJ McCull och and his men, particularly in reconnoitering … were of the highest importance.”9 The American general continued to ad vance his infantry regiments west along the Rio Grande toward Camargo, Mier and the provincial capital of Mon terrey through early July with McCull och’s men riding ahead. The newly ar rived 2nd Regiment, Texas Mounted Ri fles, now followed the invading col umn’s trail, passing through Reynosa on July 24, while 1st Regiment, Texas Mounted Rifles, continued its march from south Texas toward Matamoros. McCulloch again proved useful during this movement with another reconnaissance, this time focusing on the northern “China Road.” When the scouts disqualified the use of that way due to restrictive terrain, Taylor noted that the Texans had “given valuable in formation touching on one of the routes to Monterrey.”10 By late August, the main infantry bri gades, artillery companies, engineer detachments, McCulloch’s and Price’s scouts and, more importantly, the 10 mounted companies of 2nd Texas had consolidated at Camargo. This placed most of the expeditionary force about halfway to the strategic objective at Monterrey. Taylor then employed Figure 2. Overview map showing U.S. forces’ movements into Mexico. Movements of units mentioned in this article are on the central-eastern side of Mexico. (Map courtesy of Wikimedia, https://upload.wikimedia.org/wikipedia/commons/ thumb/0/0b/mexican–american_war_%28without_scott%27s_campaign%29-en.svg/2000px-mexican–american_ war_%28without_scott%27s_campaign%29-en.svg.png)

Fall 2019 McCulloch to assess the next route, this time to Mier and Cerravlo, while reporting that 2nd Texas was “rendering useful service as escorts.” The veteran Ranger company also officially reorga nized into 1st Texas Regiment under an other famous Texan, COL John Coffey Hays, during this time.11 While 2nd Texas provided close support to the army’s infantry brigades, the eight companies of 1st Texas secured the army’s southern flank. Taylor not ed that the mounted regiment was “on its march from Matamoras, having tak en San Fernando along its route, which passed through a part of the country not before examined.” A journalist from The Picayune (New Orleans) newspaper reported the Texans would “take up the line of march again to morrow and move for a town called China, about 150 miles from this place.” He also noted that “at China, the regiment will probably join the main body of the army.” Reid simply called the maneuver a “long scout.” This circuitous movement cleared a large tract of enemy Mexican guerril las while preventing an organized sur prise attack against Taylor’s extended lines of communication.12 On Aug. 19, the American column veered away from the Rio Grande and toward the prize of Monterrey. While most of 1st and 2nd Texas moved as in tact regiments, the general retained McCulloch’s company and another led by former Ranger G.A. Gillespie to ex plore the remaining route to Monter rey. The scouts patrolled southwest and arrived at the town of Cerralvo Sept. 5 with the lead infantry regi ments close behind. The long train of American foot and cannon units soon closed in and established a temporary camp. The 1st Texas, still guarding the army’s southern flank, skirmished against Mexican cavalry to the south during this period, losing three men but fulfilling its mission.13 On Sept. 15, the twin Texan regiments consolidated as a volunteer brigade of mounted rifles under nominal com mand of Texas Gov. James Henderson and moved to converge with the main column at Marin. PVT James Holland, a volunteer enlisted scout from Harri son County, TX, recalled that a detach ment of “about 100 men were ordered in advance as spies.”14 McCulloch’s and Gillespie’s companies remained de tached from the ad hoc brigade to work directly for the commanding gen eral. As Taylor’s trusted scouts, they patrolled ahead to meet their parent regiment in Marin. Once there, Taylor issued the order of battle and the plan for the expected assault on Monterrey. On Sept. 14, while leading the Ameri can advance, McCulloch’s riders con ducted effective counter-reconnais sance by defeating a larger Mexican cavalry force near Marin. Reid de scribed how the enemy horsemen “opened fire with their escopetas, or carbines, which was returned by our boys in a most spirited manner.” He then wrote that “the Mexicans stag gered under our fire and retreated into the town in the greatest confusion.” With the Mexican scouts in retreat, the Texans advanced to occupy the town Sept. 15, only 25 miles from the pro vincial capital. Though just a skirmish, this engagement underscored the le thality of the Texans’ Colt revolvers and degraded the Mexican commander’s ability to observe the invader’s ap proach.15 The American army arrived in Marin in separate brigade columns over the next few days, while Taylor again em ployed his Texans to scout ahead, this time as his personal escort to facilitate a commander’s reconnaissance. As chronicled by Dana, “As soon as GEN Taylor arrived at his camp, he and an escort of dragoons and two companies of Texas Rangers went to reconnoiter the enemy’s positions.” This action fa cilitated the final refinement of the battle plan as the commander and his staff officers saw the objective for the first time. On Sept. 18, the full Lone Star Brigade arrived at the American camp, bringing the expedition to more than 6,000 men.16 The expedition began its final march south toward Monterrey Sept. 19. Tay lor ordered the “Texas mounted troops” to “form the advance … except for two companies to compose the rearguard.” This directive preserved the infantry and dragoons from fatigu ing advance and rearguard security du ties while retaining them in close-order formation for the impending assault. The Texans’ sequence of march as the army’s vanguard consisted of Gil lespie’s company, McCulloch’s compa ny, 1st Texas Regiment and 2nd Texas Regiment. Taylor followed with three infantry divisions comprised of regu lars, followed by several volunteer in fantry regiments.17 The consolidated weight of the Ameri can army now advanced inexorably to ward its objective. As remembered by Walter Lane, a young Texas Revolution veteran riding with 1st Texas, the inva sion force marched “as if it were like the ocean’s swell” and “formed a noble and imposing pageantry.” Most Sol diers were eager to participate in what they expected to be the culminating battle of the war. Another scout re counted how the Mexican cavalry “in proud array, with lances bright,” con tested the advance. The Texans were soon “charging at full gallop,” and the enemy was “seen to wheel and retreat toward the city.”18 When the Texans reached the hill overlooking Monter rey, they halted to allow Taylor’s staff engineers, which included future Con federate GEN Robert E. Lee, to conduct a final assessment of the daunting for tifications.19 This final act of counter-reconnais sance on behalf of the expedition al lowed the line regiments to deploy un molested from line-of-march to attack positions along advantageous ap proaches. In the following days, the consolidated army – relatively un scathed and unfatigued in large part due to the Texans’ reconnaissance-pull actions – would attack and capture one of Mexico’s greatest urban centers with a bold plan that fixed the garrison to the east while enveloping from the west. Despite its massive fortifications and more than 10,000 defenders, which one Soldier called a “second West Point in strength,” Monterrey would soon fall under a series of bloody assaults that swiftly led to its capitulation.20 The American army then proceeded to occupy the city and the entire Rio Grande corridor in hopes of compelling diplomatic concessions. Follow-on operations After the capture of Monterrey, the Lone Star mounted brigade emerged as a liability for Taylor in the next phase of the conflict. In addition to the

Fall 2019 army no longer requiring their forward reconnaissance services, the volun teers’ indiscipline and brutality toward Mexican civilians had become a liabil ity for stability operations. As their ex cesses threatened to rouse the indig enous populace, the general com plained in exasperation that “the mounted men of Texas have scarcely made one expedition without unwar rantedly killing a Mexican.”21 With the war seemingly won, he dismissed most of the Texas volunteers to return to their homes on the western frontier. However, the American occupation force soon learned that major combat operations were far from over. In January 1847, suspicious of a Mexican counter-offensive and again lacking proficient scouts, Taylor re-enlisted McCulloch’s proven company to screen the vast expanse of Mexican territory to the south. As the invading army spread out to patrol and guard Mon terrey, and its surrounding infrastruc ture and approaches, it remained vul nerable to concentrated attack. The Texans patrolled the southern flank of the army throughout the next month. They soon provided critical intelligence about the approach of a large retalia tory force under Mexico’s president, Antonio Lopez de Santa Anna. On Feb. 22 and 23, the American force of 5,000 Soldiers repelled the Mexican army of 16,000 soldiers in a bloody and indecisive engagement. Called the Bat tle of Buena Vista, McCulloch’s Rang ers performed light-cavalry functions before, during and after the engage ment, earning special commendation from the commanding general. Ohio officer Luther Giddings later credited “that trusty and accomplished scout, CPT McCulloch” for providing the criti cal notice of Santa Anna’s unexpected approach. The timely information col lection and reporting allowed Taylor to rapidly reposition his army to defend able terrain just prior to the battle, which allowed him to defeat the larger Figure 3. Mexican territorial claims relinquished in the Treaty of Guadalupe Hidalgo are shown in white. (From the Na tional Atlas of the United States; public domain)

Fall 2019 Mexican force and provide political le verage to leaders in Washington, DC. Past lessons, future insights The reconnaissance and security ef forts by Texan mounted volunteers in the Monterrey Campaign reveal an ob scure, thought relevant, historical ex ample where well-armed, highly mo bile and proactive cavalry forces pulled an American field army to victory. By executing route reconnaissance, coun ter-reconnaissance and mobile guard operations, the Lone Star scouts en abled the advancing infantry brigades and artillery companies to, as de scribed by U.S. Army doctrine, “achieve positions of relative advantage” across 200 miles of challenging and unknown terrain.22 The volunteers achieved this through clear understanding of the commander’s intent, tactical ability to fight for information and focus on timely and accurate reporting. The 1846 invasion of northern Mexico offers several lessons for the modern U.S. Army. First, when brigades, divi sions, corps or joint task forces ad vance into unfamiliar terrain and un predictable situations, they need re connaissance elements that are trained and equipped to “pull” them into the fight. While most ground reconnais sance efforts will likely be pushed by advancing formations with relatively developed plans, cavalry forces must prepare for the eventuality when de graded information environments re quire forward scouts to inform imma ture plans at tactical and operational levels. These instances will require mo bile elements, like the Texan volun teers in northern Mexico, to “work over a broad area to develop the ene my situation.”23 The second lesson of the campaign is fundamental to all cavalry operations. The success of the Texas volunteers – in addition to many other examples since – indicates that ground recon naissance forces must possess ade quate firepower, mobility and, in the 21st Century, passive and active protec tion to allow them to aggressively fight for information. If reconnaissance actions in past wars revealed the cost of failing to develop a versatile range of “scouting” capabilities, the uncer tainty of the future will compel squad rons to arm to negotiate it. By equip ping for both pull and push missions against the most capable threats, U.S. cavalry formations will, as mandated by GEN Mark Milley, 39th Chief of Staff of the Army, enable “sustained land operations across the spectrum of con flict and win in ground combat.”24 MAJ Nate Jennings teaches history at Command and General Staff College, Fort Leavenworth, KS. Previous assign ments include Army strategist, Com bined Arms Center, Fort Leavenworth; strategic planner in Resolute Support Headquarters, Kabul, Afghanistan; as sistant professor of history at U.S. Mil itary Academy, West Point, NY; Head quarters Troop commander and Troop C commander, 4-9 Cavalry, 2nd Brigade Combat Team (BCT), 1st Cavalry Divi sion, Fort Hood, TX, and Iraq; platoon leader, Company B, 1-34 Armor, 1st BCT, 1st Infantry Division, Fort Riley, KS, and Iraq; and 19D cavalry scout in 2nd Ar mored Cavalry Regiment (Light) with Operation Iraqi Freedom tours in Bagh dad and Kirkuk, Iraq. His military schooling includes the School of Ad vanced Military Studies, Command and General Staff Officer’s Course, Cavalry Leader’s Course, Maneuver Captain’s Career Course, Armor Officer Basic Course and Air-Assault and Airborne schools. MAJ Jennings holds a bache lor’s of arts degree in history from Northwestern State University of Loui siana and a master’s of arts degree in American history from the University of Texas at Austin. He won the Perry Prize for the best master’s thesis at the University of Texas at Austin in 2013 and 1st place in the U.S. Army Armor School’s 2015 Starry Writing Competi tion. He is the author of the book, Rid ing for the Lone Star: Frontier Cavalry and the Texas Way of War, 1822-1865. Notes 1 FM 3-98, Reconnaissance and Security Operations, July 1, 2015. 2 Charles Trower, Hints on Irregular Cav alry, Calcutta: W. Thacker and Co., 1845; Philip Haythornthwaite, Napoleonic Cav alry, London: Cassell & Co, 2001. 3 Abner Doubleday, My Life in the Old Army: The Reminiscences of Abner Dou bleday from the Collections of the New York Historical Society, edited by Joseph Chance, Fort Worth, TX: Texas Christian University Press, 1998. 4 Napoleon Dana, Monterray is Ours! The Mexican War Letters of Lieutenant Dana, 1845-1847, Lexington: The University Press of Kentucky, 1990. 5 William Henry, Campaign Sketches of the War with Mexico, New York: Harper and Brothers, 1847. 6 Samuel Reid, The Scouting Expeditions of McCulloch’s Texas Rangers, or the Summer and Fall Campaigns of the Army of the United States in Mexico, Philadel phia: John E. Potter and Company, 1885; House executive documents (HED) No. 60, 30th Congress, 1st Session. 7 Reid. 8 Ibid. 9 HED No. 60. 10 James Holland, “Diary of a Texan volun teer in the Mexican War,” Southwestern Historical Quarterly 30, July 1926; Reid; HED No. 60. 11 HED No. 60; Holland. 12 HED No. 60; Reid. 13 Henry; Frederick Wilkins, The Highly Ir regular Irregulars: The Texas Rangers in the Mexican War, Austin: Eakin Press, 1990. 14 Holland. 15 Reid. 16 Dana. 17 HED No. 60; Reid. 18 Reid. 19 Walter P. Lane, The Adventures and Recollections of Walter P. Lane, Marshall: News Messenger Pub. Co., 1923. 20 Dana. 21 HED No. 60. 22 FM 3-98. 23 Ibid. 24 GEN Mark Milley, Advance Policy Ques tion for Nominee for the Chief of Staff of the Army, July 21, 2015. Acronym Quick-Scan BCT – brigade combat team FM – field manual HED – House executive document