Following Cpt. Seth Thornton’s ambush in late April, both armies along the Rio Grande prepared for the war that, as of yet, still remained undeclared. Events were transpiring too quickly for word to get back to Washington, D.C. or Mexico City, so responsibility for decisions came to rest on the Zachary Taylor and his counterpart, Mariano Arista.
Like he had in ordering troops across the Rio Grande—the move that led to the confrontation with Thornton—Arista continued with his offensives. Rather than move his troops back to Matamoros, Arista planned his next target. Just shy of 50 miles away from the two armies sat Point Isabel, Taylor’s supply base. If Arista could capture Point Isabel, it would isolate the Americans and they would soon run out of rations, forcing a retreat back to the Nueces River, which Mexico still insisted was the true boundary between the two nations. Arista’s men set out to besiege Point Isabel.
Hearing of Arista’s movement, Taylor acted quickly. Leaving a small portion of his troops behind to man the fortifications along the Rio Grande, Taylor set-off with the rest of his army on May 1. He marched the troops hard, fearful of the ramifications if he lost Point Isabel. But when Taylor’s men reached the supply point on May 2, there were no Mexicans to be found.
Logistical problems plagued Arista’s move from the start, and intended reinforcements for the march on Point Isabel instead became bogged down in trying to cross the Rio Grande. By the time his logistics were sorted-out and Arista was ready to resume his march, it was too late. Taylor’s men had the jump now, and it would be difficult to catch up. Arista, though frustrated by the failed move against Point Isabel, did not allow it to deter him completely, and he planned a new offensive.
Arista’s new target was the series of forts and emplacements that Taylor’s men had been digging along the Rio Grande. Unlike Taylor, who only had a few hundred men to man those defenses, Mexican forces remained in the thousands within Matamoros in addition to the troops with Arista on the northern side of the Rio Grande. His numerical superiority allowed Arista to plan a quick-strike combination: Mexican guns would batter the American forts to pieces and Arista would intercept Taylor’s force as it turned around and marched back to the relief of the forts.
Mexican artillery opened fire along the Rio Grande on May 3, sending shot and shell soaring through the air. (A subsequent post will detail the fighting along the Rio Grande). In Point Isabel, the Americans could clearly hear the firing from almost 50 miles away. Each thunderous boom that the Americans heard “sent a thrill through every heart in our encampment,” 2nd Lt. Alexander Hays wrote. The Americans were eager to march back to the Rio Grande, but Taylor waited. He worried more about any other intrusions against Point Isabel, so before setting out, Taylor ordered more defenses built around the supply depot before heading out. Until then, the American detachments at the river were on their own.
Waiting for the order to move back, Lt. George Meade wrote to his wife about the bombardment of the forts. “We were obliged to leave all our baggage in the fort and in my trunk I left your miniature, bringing with me the daguerreotype.” The future victor of Gettysburg then added a little joke, “I very much fear some impudent shell has ere this blown you up, and you will have been in action before myself.”
Satisfied with the works at Point Isabel, Taylor finally ordered his men to march on May 7. His troops had been “anxiously looking for the order,” James Longstreet later wrote. Then a 2nd Lt., Longstreet added that the troops marched out “with cheers,” but those cheers subsided as an “awful” night came on. The troops spent the night slapping at mosquitoes that “seemed as thick as the blades of grass on the prairie” while “packs of half-famished wolves prowled and howled about us.” The next morning, May 8, the Americans were happy to get up, form marching columns, and continue on.
About halfway between Point Isabel and Matamoros, Taylor’s men came upon Mariano Arista’s forces arrayed in line of battle near a watering hole called Palo Alto. With some 3,700 men under his command, Arista eyed Palo Alto as the perfect place to challenge Taylor—with miles of open ground now allowing Taylor any chance to maneuver out of the fight. Marching towards the fight, Taylor would not have any more than 2,200 men to fight with.
But Taylor did have one advantage that soon introduced itself. The American artillery ranged in size from 6- and 8-pounders, with two 18-pounders, dragged by oxen, added for good measure. All of the cannons were under the command of Maj. Samuel Ringgold, who had been introducing concepts of light artillery to the long-arm’s service. Ringgold new gunnery-style had the nickname of “Flying Artillery”, and Palo Alto would be the first chance for the artillery to prove itself. Opposite them, Arista’s largest pieces were 8-pounders, with the majority of his cannons only firing 4-pounders. Ringgold had the upper-hand when it came both to range and ability to move around the battlefield.
Because he was outnumbered, and because he knew he had the heavier caliber artillery, Taylor was content to pull his men into battle lines and then wait for Arista to make the first move. Taylor organized his lines of battle so that each of Ringgold’s section of artillery was flanked by infantry to protect the guns. When the lines were set, Taylor gave the go-ahead for the guns to start firing.
“Evry [sic] moment we could see the charges from our pieces cut a way through their ranks making a perfect road, but they would close up the interval without showing signs of retreat,” 2nd Lt. Ulysses S. Grant wrote back to his wife. As the American artillery fileted the Mexican lines, the return fire did little. Future Union division commander Israel B. Richardson, then a 2nd Lt. in the 3rd Infantry, remembered that “very few of our troops were injured, as most of the shot of the enemy passed over our heads.” As the firing went on, Richardson wrote that “Our infantry was directed to sit on the ground to avoid the distant cannonade, and the battle continued with our artillery.” The infantry’s role in the beginning stages of the battle was that of “passive spectators,” Alexander Hays remembered.
The Mexican artillery did not, however, prove entirely ineffective. While the infantry ducked for cover, the American gunners tended to their pieces. Proving especially troublesome to Arista’s lines were the two 18-pounders, monsters on the field against Arista’s 4-pounders. Focusing their attention on the 18-pounders, the Mexicans did not knock them out of action, but they did get Maj. Ringgold. “About 6 o’clock he was struck by a six pound shot,” an American wrote. “He was mounted, and the shot struck him at right angles, hitting him in the right thigh, passing through the holsters and upper part of the shoulders of his horse, and then striking the left thigh, in the same line in which it first struck him.” Ringgold was brought back to camp, where his wounds proved mortal. He died on May 11, but his “Flying Artillery” had proven its worth and Ringgold, before he died, “spoke with much pride of the execution of his shot.”
After the heavy bombardment, Arista realized he wouldn’t defeat Taylor unless the American guns were silenced, and the Mexican artillery would not be able to accomplish that. He turned to his lancers and ordered the cavalry to charge the guns. As the Mexican cavalry thundered over the prairie, the American infantry rose to their feet and soon formed squares on the flanks of the guns. Squares, outdated by the time of the American Civil War, was still the best way to beat cavalry charges in the 1840s with both sides armed with smoothbore flintlock muskets. The hedges of bayonets met the Mexican cavalry head-on. Holding their fire, the Americans volleyed “when the lancers had arrived within 16 paces of the square,” Israel Richardson wrote.
His cavalry charges beaten back by the squares and solid musketry, Arista planned one last assault. Looking to his infantry, Arista ordered them forward. But the Mexican infantry had spent hours under the heavy fire of Ringgold’s guns, and they hesitated to go forward. To try and force them forward, Mexican officers slashed at their men with swords “at a dreadful rate,” Ulysses S. Grant wrote after the battle, looking at the backs of some of the prisoners captured.
Wavering under their officers’ blows, the Mexican infantry advanced but were soon “cut up by the crossfire of our artillery with grape[shot] and shrapnel shell,” bloodying the ranks and sending them back to reform and try again. But each time they went forward, the American guns roared to life and filled the air with canister rounds.
Near sundown, Arista pulled his men back out of the range of the American guns. He did not surrender the field entirely, and another battle would be necessary the following morning. But for now, the Americans took stock of the situation and their first victory of the war.
“I was in the action during the whole time, at the side of General Taylor, and communicating his orders,” George Meade wrote to his wife, “and I assure you I may justly say I have had my [baptism of fire].” Looking over the field, Lt. Grant wrote, “The ground was litterally [sic] strewed with the bodies of dead men and horses.”
The Battle of Palo Alto, the first pitched battle of the Mexican-American War, was undoubtedly an American victory, at least on the tactical scale. Strategically, Arista still blocked Taylor’s passage, but his army had been given a bloody nose. Ringgold’s heavy cannon fire caused the most damage, added in with the infantry’s repulse of the cavalry attacks. In total, Arista lost 102 killed, 129 wounded, and 26 captured. Taylor’s men, on the other hand, lost 5 killed, 48 wounded, and 2 missing.
With the heavy cannon fire at Palo Alto, the last chances for diplomacy went out the window. For over a year the two countries had squabbled, stared, and skirmished over the Rio Grande, and now they would go to war.
 The Life and Letters of General Alexander Hays, 58.
 The Life and Letters of George Gordon Meade: Vol. 1, (New York: Charles Scribner’s Sons, 1913) 77.
 James Longstreet, From Manassas to Appomattox (Philadelphia: J.B. Lippincott Company, 1908), 24.
 Douglas A. Murphy, Two Armies on the Rio Grande (College Station: Texas A&M University Press, 2015), 166-168.
 The Papers of Ulysses S. Grant, Volume 01: 1837-1861, Edited by John Y. Simon, Southern Illinois University Press, 84-85.
 Jack. C. Mason, Until Antietam: The Life and Letters of Israel B. Richardson ( Carbondale: Southern Illinois University Press, 2009), 20.
 Hays, 60.
 Niles’ National Register, May 30, 1846 “Death of Major Ringgold.”
 Mason, 20.
 Mason, 20-21.
 Meade, 80; Grant, 85.
 K. Jack Bauer, The Mexican War: 1846-1848 (Lincoln: University of Nebraska Press, 1974),57.