ON MAY 9, 1846, Captain Ephraim Kirby Smith awoke on the field of Palo Alto, Texas, among the men of his company of the Fifth Infantry regiment. Kirby had returned to the Army several years after his court martial for flogging troops after the Fort Mackinac mutiny sixteen years earlier. He spent another decade and a half on the frontier, in Illinois, Wisconsin and Minnesota, still frustrated at the path his military career was taking. He was not called to fight in his family’s home territory of Florida and did not volunteer to go either. Yet on this morning, in this dry, beaten field, two months shy of twenty years since he left West Point, Kirby had reason to be proud. The previous day, outnumbered American forces under the command of Brigadier General Zachary Taylor, moving to lift the siege of Fort Brown on the Rio Grande, fought Mexican troops under General Mariano Arista to a standstill, in the first major engagement in the as yet undeclared war with Mexico. It was Kirby’s first taste of battle.¹

      Palo Alto was in the main an artillery duel. The infantry spent the day in line or square, watching the distant movements of the Mexicans in their resplendent uniforms, warding off cavalry attacks and protecting the artillerymen as they delivered their deadly fire. It was also an eventful day for Major Samuel Ringgold, fifth in Thayer’s first class of 1818, a pioneer in the development of light artillery tactics.² The American guns were smaller, but more mobile and swiftly reloaded. Ringgold had developed methods of fire and maneuver that made his light cannon more lethal than the heavier, more ponderous Mexican pieces. Red-flannel-shirted gunners moved their guns, unlimbered, loaded, fired a few rounds, then limbered to move to new positions before the enemy batteries could bring them under counterfire. Before Palo Alto, this had been only a concept, but there it was tested in warfare and proved its worth under Ringgold’s deft and daring leadership. He was assisted by his junior officer, Lieutenant Randolph Ridgely, the determined Immortal of the Class of 1837 who suffered through three plebe years. Throughout the battle, cannonballs fell amidst infantry drawn up in close order, ricocheting into packed bodies of men, or skipping harmlessly past them into the tall dry grass. “The enemy’s shot were playing briskly through our ranks,” Kirby wrote, “the wounded and dying at our feet producing no effect upon the admirable discipline of the men.”³

      After an hour of dueling, a smoldering wad from one of the American guns landed in some scrub and the wind-whipped prairie caught fire. The spreading flames and heavy smoke forced a pause in the fight, and each side sought to maneuver to advantage under cover. After the fire moved on, the battle reignited, raging through the afternoon and into evening. When a large force of Mexican cavalry threatened on the right flank, Taylor dispatched the Fifth Infantry to intercept them. Kirby’s company rushed across a quarter mile of prairie to meet the advancing dragoons. “Here they come!” someone shouted, and the infantrymen formed a square, standing shoulder to shoulder in multiple lines, muskets poised, bayonets bristling. The mass of cavalry, eight hundred strong, rode towards them at a gallop, then at a charge. At one hundred feet out, the Mexicans fired their side arms, drew sabers and kept coming. Some Americans fell, but the rest stood coolly, and a moment later returned a devastating volley. Off to the right, twenty mounted Texas Rangers under Captain Samuel H. Walker picked off Mexican officers with deadly-accurate rifle fire. The horsemen veered left, and were met by raking canister fire from two of Ridgely’s field pieces, sending the cavalry back to their lines in a rout. It was Kirby’s baptism of fire. “The spectacle was magnificent,” he wrote. “The prairie was burning brilliantly between the two armies and some twenty pieces of artillery thundering from right to left, while through the lurid scene was heard the tramping of horses and the wild cheering of the men.”⁴

      Combat ended when darkness fell. The Mexicans got the worst of it, but many Americans fell as casualties too, among them Ringgold himself—hit in the side of the leg by a Mexican cannonball that passed through his horse and blasted out through his other thigh. He was taken from the battlefield, surprisingly calm. Ringgold lived for sixty hours, cheerful to the end. Back on the field, soldiers worked by the orange light of the retreating prairie fire, treating wounded and burying the dead. The infantry made bivouac in their squares, sleeping on the ground, on their muskets, mindful of the enemy still on the field. It was a clear, cool night, the moon gently lighting the battlefield behind wisps of smoke. The air was tainted with the smell of burned grass and gunpowder. From both sides came the sounds of the wounded, the dying, or those suffering under the surgeon’s saw.

      When morning broke the next day, the Mexicans had departed, slipping from the field unnoticed and withdrawing down the road towards the Rio Grande and their headquarters at Matamoros. After a quick breakfast, Taylor called his senior commanders together for a council of war. Ringgold was not present—he was in the hospital tent at the moment, showing signs of improvement, attended by his friend Ridgely, who had assumed command of the battery. Ridgely said he hoped “old Zack will go ahead, and bring the matter to close quarters.” But few other officers agreed. The Mexicans had removed to a stronger defensive position, closer to their base of supply and reinforcements, and to the besieged Fort Brown. The Americans were still outnumbered and would have to leave their pack train behind, along with a force to protect the supplies and the wounded. The odds did not look good. Nine of Taylor’s commanders advised either entrenching to await additional troops, or withdrawing to the supply head at Port Isabel. Only four voted in favor of renewing the battle. Taylor listened pensively to the arguments and concluded the council by saying, “I will be at Ft. Brown before tonight, if I live.”

      Manifest Destiny

      IN 1844, THE REPUBLIC OF TEXAS was a sovereign state, recognized by the United States, Britain and France, but not by the country from which it won independence, Mexico. The Tyler administration had sought to annex Texas and negotiated a treaty to that effect. To deter Mexico from seeking to reconquer its wayward northern province, Tyler sent a secret “Corps of Observation” to the border, commanded by brevet Brigadier General Zachary Taylor, hero of Okeechobee. But when the annexation treaty went before the Senate in June, Tyler suffered a setback. Sectional issues, particularly the understanding that Texas would be admitted as a slave state, coupled with divisions within the Whig party, led to a 35 to 16 defeat.

      The slaveholding states, greatly outrepresented in the House, sought to maintain parity in the Senate in order to block any legislative efforts to end their “peculiar institution.” Florida was on the verge of statehood, and the accession of Texas and lands to the west would supply territory out of which could be carved future slave states, to prevent a free state lock on government. The issue was thrown into the cauldron of the 1844 presidential race. James K. Polk, a protégé of Andrew Jackson’s, known as “Young Hickory,” ran on an annexationist platform, seeking to balance sectional feelings by also making an issue of the Oregon boundary dispute with Britain, coining the expression “54’40” or Fight!” Whig candidate Henry Clay, who opposed annexation, tried to straddle the issue, but wound up alienating his abolitionist base and lost the election.

      Annexation was voted on again in a controversial joint resolution that President Tyler signed March 1, 1845, three days before leaving office. The offer was taken to Texas by the chargé d’affaires, Andrew Jackson Donelson, nephew of the former president and second-ranked graduate of the USMA Class of 1820, whom Thayer had attempted to expel.⁵ A July 4 popular convention in Austin approved the offer, and Texas was formally admitted to statehood on December 22, 1845.

      The resolution admitting Texas left an important omission: it did not define the southern border of the new state. Texas claimed all lands south to the Rio Grande, and Mexico claimed the area north to the Nueces, a matter of thousands of acres of sparsely inhabited, lawless