War with Mexico! The Battle of Palo Alto, 8th May 1846

Being a replay in miniature of the first clash of the Mexican War along the Rio Grande between the forces of the United States and the Republic of Mexico using the rules Volley & Bayonet II, Age of Napoleon ™, developed by Eric Ackermann, Esq.

Background:

Tensions between the United States and Mexico over the location of the southern border of Texas had been simmering for years, ever since Texas independence in 1836 and its subsequent annexation by the United States in 1845. Repeated efforts to settle the dispute peaceable, usually offers by the Americans to buy the territory, came to naught. Once the United States peaceably settled its dispute with Great Britain over the border between the Oregon Territory and Canada, it was free to deal with Mexico.

In 1845 the Army of Observation was formed by the United States and placed under the command of Brigadier General Zachary Taylor. It was ordered to the edge of the disputed southern Texas border at Corpus Christi. The army was completely composed of regular army formations. Learning nothing from the experiences of the War of 1812, the status of the regular army was precarious, with frequent efforts mounted in the US Congress to have it abolished. The creation of this all regular field army was seen as a test case for it viability. Success in war would insure its continued survival, as well as that of the West Point Military Academy. Failure would mean its eventual demise.

General Taylor moved quickly to convert the Army of Observation to the Army of Occupation by moving into the disputed territory on March 8, 1846 He reached Port Isabel on the Gulf of Mexico later in the month. Here Taylor rendezvoused with the US Navy carrying his supplies and heavy artillery, and established his base of operations. On March 28, 1846, Taylor moved his army to the Rio Grande, the border claimed by the United States. At a point opposite the Mexican city of Matamoros, Taylor built Fort Texas and garrisoned it with the 7th Infantry Regiment, Lt. Braxton Bragg’s Company of Light Artillery, and a heavy artillery company of 18 pdrs, all under the command of Major Jacob Brown. Across the river in Matamoros, Taylor’s counterpart, Major General Mariano Arista and the Army of the North waited.

The Mexicans struck first. Brigadier General Torrejon and a force of 1600 Mexican cavalry and light infantry crossed the Rio Grand downriver from Matamoros. They successfully ambushed a patrol of US Dragoons, killing or capturing over 70 men.

General Arista and the rest of the Mexican Army soon crossed the Rio Grande intending to cut Taylor and the Americans off from their base at Port Isabel. Port Isabel was not yet fortified and could not withstand an attack by the Mexican Army. Alarmed, Taylor threw supplies into Ft. Texas, and force marched the US Army to Port Isabel. Poor staff work in organizing the river crossing by the Mexican Army gave the Americans just enough time to escape the trap. General Arista detached 1600 men to put Ft. Texas under siege and maneuvered the remained to the army to intercept any American force from Port Isabel.

Taylor assembled a relief force of 2250 men and almost 300 wagons and marched for Ft. Texas. Arista positioned the Army of the North across the only viable wagon route to Ft. Texas. Summoning most of the troops besieging Ft. Texas, he waited for the US Army at Palo Alto. Outnumbering the Americans by almost two to one, Arista drew up his army in a single battle line with no reserves, allowing the US Army to deploy unmolested from a line of march. Taylor was determined to carry the fight to the Mexicans, and deployed for an assault.

Taylor planned to strike his right, launching a bayonet charge straight at the Mexican center. He would refuse his left wing, covering it with a cavalry screen. Arista deployed expecting this attack, planning to counterattack it on both flanks. The battle opened at about 3pm with an exchange of artillery fire. Neither side anticipated the startling mobility and firepower of the American light artillery. Unable to respond effectively with his own artillery, Arista tried to counter by launching his left wing cavalry in a flank attack on the American right. Unfortunately for the Mexican cavalry, crossing the resaca proved more difficult and time consuming than anticipated. By the time the cavalry extracted itself and formed for the attack, the 5th US Infantry Regiment, backed by Ringgold’s Light Artillery Company of 6- and 12 pdrs, was ready and repulsed two Mexican charges. The remaining cavalry then fell back behind the Mexican center.

At this point about 4pm the grass caught fire between the American right wing and the Mexican center, ignited by the smoldering wadding from the US cannon and fanned by the easterly wind. A lull in the battle ensued, with both sides shifting forces toward their respective right wings. When the fire subsided about an hour later, both sides attacked the left wing of their opponent’s army. On the American left, Duncan’s Light Artillery Company enfiladed the Mexican attack, routing the Light Mounted Regiment of Mexico through the attacking Mexican infantry, forcing it back in disorder. Meanwhile, the American advance on the Mexican left was halted by intense, close range cannon fire by the Mexican field artillery.

The overall combination of the relentless American artillery fire and the failure of both flank attacks proved too much for the Mexicans, who began to withdraw from the battlefield about 7pm. Exhausted themselves, the Americans did not pursue, and fell back on the wagon train. Casualties were light for the Americans (less than 45), and much heavier for the Mexicans (about 250). The battle was a draw, with the Mexican Army battered, but intact. The road to Matamos and Ft. Texas was still closed. The American spent the evening preparing for renewed fighting on the following morning. However, Arista opted instead to withdraw his army to a new defensive position at Resaca de Palma.

Arista missed several opportunities offered to him. He failed to harass a long and difficult to defend US supply train, nor did he attempt to interfere with the deployment of the US Army which he could have easily done. Once the battle commenced, Arista remained passive too long under the pressure of intense artillery bombardment. When he finally did attack, first with the cavalry on his left, then with his infantry on his right, he did so piecemeal, with unsupported and uncoordinated attacks. This allowed the Americans time to react and defeat each attack in turn. The Americans in turn were slow to develop their own assault, never really following up on the repulsed Mexican attacks. Instead, Taylor preferred to let his fine artillery carry the burden of the battle.

Orders of Battle:

Reduced Battalion Scale = 50 yards, 1 turn = 30 minutes, 1 sp = 100 men or 2 guns, stands = massed unless otherwise noted.

Abbreviations: efd = early firelock drill, fld = field; lt = light, med = medium, hvy = heavy, ne = no elites present in unit, ppa = pre-professional artillery, pt = poorly-trained, sh = shock, sk = can break into skirmish stands, lncr = lancer, mil =militia.

MEXICAN ARMY OF THE NORTH, Maj. Gen. Mariano Arista, Army Commander (2,500 infantry, 1100 cavalry, 400 irregular cavalry, and 10 guns) 

Left Wing, Brig. Gen. Anastasio Torrejon, DC Ex = 4 [6]

  • Presidial Light Cavalry (200)              M5 [][] lt lncr
  • 1st Line Cavalry Regiment (200)            M5 [][] lt lncr
  • 8th Line Cavalry Regiment (200)            M5 [][] lt lncr
  • 7th Line Cavalry Regiment (200)            M5 [][] lt lncr
  • Mounted Aux. Regt de las Villas del Norte  M4 [] lt lncr, mil (linear stand)
  • Left Wing Horse Artillery Section          M5 [] lt (horse artillery 2 x 4 pdrs) (see notes)
  • Irregular Cavalry (“Rancheros”) (400)      M4 [][] lt lncr, mil (see notes)                                                                          M4 [][] lt lncr, mil  

Center, Brig. Gen. Jose Maria Garcia, DC Ex = 7

  • 4th Line Infantry Regiment (500)           M5 [][][][][] efd
  • Field Artillery Section (2 x 8 pdrs)       M5 [] fld, ppa
  • 1st Line Infantry Regiment (400)           M5 [][][][] efd
  • 10th Line Infantry Regiment (400)          M5 [][][][] efd
  • Light Artillery Battery (4 x 4 pdrs)       M5 [][] lt, ppa

Right Wing, Brig. Gen. Romulo Diaz de la Vega, DC Ex = 7

  • 6th Line Infantry Regiment (300)           M5 [][][] efd
  • Tampico Coast Guard Battalion and Veteran Coast Guard Company (400)                                      M4 [][][][] ne, pt, efd
  • 2nd Light Infantry Regiment (300)          M6 [][][] sk (see notes)
  • Zapadore (Sapper) Battalion (300)          M6 [][][] sh, efd
  • Right Wing Artillery Section (2 x 4 pdrs)  M5 [] lt, ppa
  • Light Mounted Regiment of Mexico (200)     M4 [][] lt lncr

Mexican Notes:

1. All small arms and cannon are smoothbore. Mexican muskets were worn Napoleonic War British surplus weapons that fired inferior quality powder. Therefore with the exception of the light infantry, they are rated “efd”, and roll one less die in stationary fire and melee combat. With the exception of the horse artillery, Mexican artillery lacked sufficient horses to make them mobile during battle, and are rated “ppa”. Once placed at the beginning of the game, they can only move by prolonging. They pivot and change facing normally for their type.

2. The Mexican “army” is only a division sized unit. The wing and brigade commanders function as divisional commanders. Garcia’s command of the Center and de la Vega’s command of the Right Wing is somewhat speculative, but possible given that the only other available general (Maj. Gen. Pedro Ampudia) was a relatively unreliable political rival of the army commander.

3. The units are listed in order of historical deployment, from left to right. Unless otherwise noted, all are considered to have elites present.

4. The Right Wing Artillery historically was only one gun, while De La Vega’s Brigade artillery battery was 5 guns. For this OB, one gun was moved from the later to bring the former up to section strength.

5. Exhaustion varies between 40% and 45%. The Center (Garcia) is about 45% , as stood under intense artillery fire throughout most of the battle without breaking, while taking most of the casualties received by the Mexican army during the battle. The Right Wing (De La Vega) is also about 45% as it did contain the two elite units, but didn’t perform as well as expected historically. The Left Wing cavalry command is exhaustion is 40%.

6. Estimated strengths for many the units vary significantly from those give by Adams (1998), whose unit strengths don’t always add up to the army totals he gives. The unit strengths used here were based on the total given by Arista afterwards, about 3700 men (Haecker & Mauck, 1997), which is assumed to exclude any irregular cavalry which did not participate in the battle. Of these 3700 men, about 1100 were cavalry, assumed to be distributed evenly among the five regular cavalry units. The remaining 2600 men are assumed to be infantry. Following Adams (1998), five hundred of these belonged to the 4th Line Regiment, leaving 2100 in the remaining six regiments, giving each a minimum of 300 men. The first 100 of the remaining 300 men goes to the poorest quality infantry unit the Tampico Coast Guard Battalion while allotting no additional troops to the two elite units on the assumption that lesser quality units tend to be larger than elite units, all other things being equal (see Chadwick and Novak, V&B II, p.63). This also makes the strength of the TCGB more in line with most of the other active militia units in the area. The final 200 were given to two of the remaining regular line infantry. Players who disagree with this can of course adjust the unit strengths to suit their interpretations of the sources.

7. The Irregular Cavalry (“Rancheros”) were led by a Brigadier General cum lawyer with a questionable reputation named Antonio Canales. He kept them out of the battle, hoping to strike a deal with the US Army that would leave him in charge of the newly liberated Mexican territory. However, he could have intervened at any time, if he thought it might be to his advantage to do so. Therefore, this unit can be handled one of two ways. It either can be omitted from the game altogether, in which case the Left Wing has an exhaustion of 4, or they can begin the battle uncommitted. If so, beginning with Turn 1, roll once per Mexican movement phase in which the Left Wing’s morale is not collapsed. 

Result of: 

  • 1 or less = Adios! Rides off into the sunset (remove from table)
  • 2-4 = still neutral, roll again next turn
  • 5, 6 = Amigos! Immediately comes under control of the Mexican Left Wing, which now has an exhaustion of 6.

Subtract 1 from the roll if the Mexican Left Wing is exhausted; if collapsed remove the Rancheros from the game. Add 1 to the result for each US command collapsed. 

Note that this can cause the Left Wing to become “unexhausted” if exhausted. Also note that the Rancheros will automatically join the Mexicans if fired on or meleed by the US.

8. The 2nd Light Infantry Regiment was used exclusively as line infantry in this battle. However, it was trained to break down into skirmishers. For the Mexicans to use this option, it must either be agreed upon mutually, or decided by the referee, before the game starts.

UNITED STATES ARMY OF OCCUPATION, Brigadier General Zachary Taylor, Army Commander (1900 infantry, 300 cavalry, and 10 guns).

  • Right Wing, Col. David E. Twiggs, AC Ex = 5 (see notes)
    May’s US Regular Dragoon Squadron (175)   M6 [][] med
  • Ker’s US Regular Dragoon Squadron (85)    M6 [] med (linear stand)
  • 5th US Regular Infantry Regiment (400)    M6 [][][][] sh
  • Ringgold's Light Artillery Company        M6 [][] fld (horse artillery 2 x 6 pdrs & 2 x 12 pdrs)
  • Walker’s Texas Ranger Company (25) Not represented (see notes)
  • Supply Train (c. 270 wagons) (see notes)

Center, Lt. Col. John Garland, DC Ex = 5

  • Churchill’s Heavy Artillery Company       M6 [] hvy (2 x 18 pdrs)
  • 3rd US Regular Infantry Regiment (400)    M6 [][][][] sh
  • 4th US Regular Infantry Regiment (400)    M6 [][][][] sh

Left Wing, Lt. Col. William G. Belknap, DC Ex = 5

  • US Regular Artillery Battalion (300)      M5 [][][]
  • Duncan’s Light Artillery Company          M6 [][] fld (horse artillery 2 x 6 pdrs & 2 x 12 pdrs)
  • 8th US Regular Infantry Regiment (400)    M6 [][][][] sh

US Notes

1. All small arms and cannon are smoothbore. Exhaustion is 50%.

2. Churchill’s Heavy Artillery Company was pulled by oxen, so has a normal limbered movement rate of 8”.

3. Duncan’s and Ringgold’s Light Artillery Companies move as horse artillery.

4. The US “army” is only a division sized unit. The wing commanders function as divisional commanders. Historically, the General Taylor left Col. Twiggs to manage the battle. To reflect this, Twiggs is listed as the AC. Taylor will only function as the AC if Twiggs’ stand is eliminated.

5. The units are listed in order of historical deployment, from left to right beginning with the 5th US Regular Infantry Regiment. It reflects the original American OB as much as possible. Unless otherwise noted, all are considered to have elites present.

6. The wagon camp consisted of approximated 270 wagons with their associated civilian drivers and draft animals assembled hastily from a line of march without time to form it into a defensible position. It is represented by a 9” x 9 “square” of wagons with a 3” x 3” space in the middle. The wagon camp is no obstacle to movement (except artillery is prohibited from entering or passing through), has no intrinsic garrison, but causes a formed unit to be disordered, and disordered unit to remain so until after it leaves the camp. The wagon camp offers limited protection against fire (i.e., a saving throw), and none against melee combat.

7. Walker’s Texas Ranger Company (R) is too small to represent on the table as such. Stationed in the mesquite to right of the US Right Wing (T), they did perform an important scouting function during the battle. They allow the US commanders to “see” what is going on the other side of the mesquite (south and west of R). This rule is a compromise. To represent them as a linear cavalry stand (1-6 Med) would not only exaggerate their presence, but also give the US an additional strike unit they didn’t have. This rule allows the Texas Rangers to play their roll in the battle without overstating their effectiveness.

Scenario Notes:

1. The battle begins at 3:00 pm, and ends at the end of the 7pm turn, for a total of 8 turns. The US is the attacker and moves first. The Mexicans begin stationary.

2. Victory determination.

Points are gained for the following accomplishments:

1 pt. for each enemy command exhausted

2 pts for each enemy command collapsed or destroyed completely

6 pts. for controlling at game’s end the Matamoros Road from Palo Alto Pond to its exit off the Mexican table edge. The Mexicans start the game in control of the road (6pts). Control determination: The Mexicans have control if they have in command at least one unrouted infantry or cavalry unit, or artillery unit supported by (in base contact with) at least one unrouted infantry unit, within 8” of the road and visible from it.

up to 9 pts. for control of the US Supply Train. Control determination: The US begins the game with control of the supply train (9 pts.). The first turn the Mexicans seize control of the supply train, they immediately receive 3pts from this total. (This represents the flight of the wagon drovers and the stampeding of their draft animals). For each turn thereafter that the Mexican side occupies the supply train, they receive an additional 2pts. from the remaining total until it reaches 0 (zero) or they loose control of the supply train to the US. (These turns do not have to be consecutive to count). If the Mexicans control the supply train at the end of the game, they get all the remaining points (if any).

1 pt each to the US for the capture and holding (i.e., being the last to pass through) the Mexican army camp, hospital, and artillery park by the end of the game. Once captured by the US, they can be recaptured by the Mexicans by being the last to pass through them by the end of the game.

Each side totals up their points. Subtract the lowest total from the highest total and consult the consult the following chart:

3 pts or less = Inconclusive engagement (no winner). Both sides stay on the battlefield that night to recover casualties and rest. The battle may continue the next day if both sides agree.

4- 8 pts = Tactical (battlefield) victory for the side with the greatest number of points. Loser withdraws from the field with their army in tact.

9 pts or more = Major victory for the side with the greatest number of points. If the winner is the Americans, the Mexican Army is in rout, the road to Matamoros is open, the siege of Fort Texas (now Fort Brown) is lifted, and General Aristas is recalled in disgrace. If the Mexicans win, the US Army is in rout, the road to Port Isabel is open, and Fort Texas will surrender. Zachary Taylor faces recall, his future political aspirations crippled. Political pressure in Congress escalates rapidly to abolish both regular US army and the West Point Military Academy.

3. The spring rains had been heavy this year. The US Heavy Artillery section (Churchill’s) must begin on the all weather road. If it leaves this road, it will immediately bog down in the soggy soil. Once bogged down, it cannot move for the rest of the game, though it may pivot/change facing normally.

4. The areas of the map that are not mesquite, road, or ponds are covered with a sharp, stiff, waist high grass that made movement difficult. A stand can move up to half its non-road movement (including any changes of facing) without becoming disordered. If it moves more than half it becomes disordered, as it would if it changed facing, moved half, then changed facing again.

5. Resaca is a depression or gully that was once a river bed filled with mesquite (thick brush and small trees.) Movement through the mesquite is half-move for all skirmishers. For each formed infantry, cavalry and artillery stand, roll one die upon entering the feature: (+1 for each stand crossing in same spot):

1-2 = cross, -1/2 move

3-4 = cross, -1/2 move, disordered

5+ = entangled in feature, loose all remaining movement. Next turn can leave -1/2 move, disordered.

6. The US Army is qualitatively superior to the Mexican Army. However, the latter’s large commands and higher exhaustion levels allow it to take a tremendous amount of punishment and keep on fighting. The Mexicans must make the most of this and their advantage in numbers of cavalry and infantry by taking the battle to the Americans, attacking them in a coordinated fashion in as many places as possible. This will stretch them thin, producing gaps that can be exploited to reach and destroy the wagons. The Americans must parry these thrusts and cover the wagon train while keeping pressure on the Mexican center with an eye to clearing the Matamoros Road. This battle has been played four to five times, with victory usually in doubt until the end.

The Battlefield and Deployment of Troops

The map is based on the work Haecker & Mauck (1997) rather than the more often used one by Ramsey (1970). 

US Army deployment:

1. Wagon camp begins the game at W. It cannot move. It cannot begin the game garrisoned. Gen. Taylor starts the turn in the wagon camp.

2. Dragoons start on either side of the wagon camp, May’s on the right side at M, Ker’s Squadron on the left at K.

3. Right Wing (Twiggs) excluding May’s and Ker’s dragoons deploys in area T.

4. Center (Garland) deploys in area G.

5. Left Wing (Belknap) deploys in area B.

Mexican Army deployment:

1. Irregular Cavalry “Rancheros”) deploys in area 1.

2. Left Wing (Torrejon) deploys in area 2.

3. Center (Garcia) deploys in area 3.

4. Right Wing (De La Vega) with Gen. Arista deploys in area 3 to the right of Garcia.

5. The Mexican camp is deployed behind the army at C, the hospital at H, and the wagon/artillery park at A.

Sources

Adams, Anton. (1998). The War in Mexico. Chicago, IL: The Emperor’s Press.

Haeker, Charles M. & Jeffrey G. Mauck. (1997). On the Praries of Palo Alto, Historical Archaeology of the U.S.- Mexican War Battlefield. College Station, TX: Texas A&M Press.

Ramsey, Albert C. (Ed. & trans.). (1970). The Other Side: Or Notes for the History of the War Between Mexico and the United States. New York: Burt Franklin Press.

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