In April 1846, Mexico declared war against the United States, marking the beginning of the Mexican-American War on the Plains. President James Polk swiftly called for 50,000 volunteers a month later, setting in motion a significant campaign in the American West. General Stephen W. Kearny was appointed to command the forces designated for Western action, his command strategically divided into three distinct divisions. Kearny himself led the first division, charting a course for the Pacific coast; Colonel Alexander W. Doniphan was tasked with leading a thousand volunteers towards Chihuahua; while the third division, under Sterling Price, was charged with garrisoning Santa Fe and securing control of New Mexico.
Early Movements and the March Westward
An intriguing anecdote from Colonel Henry Inman describes a vision experienced by a caravan of 29 traders in the spring of 1846, before war was declared. Just after a storm and near sunset, they witnessed a perfect, distinct image of the American eagle on the sun’s disc. This prompted them to declare, almost instinctively, that within a year, the ‘Eagle of Liberty’ would spread its plumes across the Western Plains, and the flag of our country would wave over the cities of New Mexico and Chihuahua. The veracity and fulfillment of this prophetic vision are left to the reader’s judgment.
General Kearny’s forces, known as the Army of the West, began their arduous march across the prairie from Fort Leavenworth, Kansas, in detached columns during the summer of 1846. This formidable expedition comprised two batteries of Artillery, three squadrons of the First U.S. Dragoons, the First Regiment of Missouri Cavalry, two companies of infantry, and a detachment of Topographical Engineers. By August, this entire force had converged in a camp on the historic Santa Fe Trail, approximately nine miles below Bent’s Fort, Colorado, situated on the Arkansas River. The detailed accounts of this extensive march across the Plains were meticulously recorded by Lieutenant W.H. Emory, commandant of the Engineers, and John T. Hughes of the Missouri Cavalry.
Initial planning for this ambitious expedition raised serious concerns among officials regarding the feasibility of moving such a large body of troops over an uninhabited wilderness, without a secure base of supplies or any possibility of reinforcement. It was considered an experiment and a dangerous one. Nevertheless, an immense quantity of provisions was transported in large, carefully guarded wagons, and beef cattle were driven alongside, subsisting entirely on the nutrient-rich buffalo grass along the trail. At night, these cattle were typically confined within a corral formed by the wagons, though occasionally tethered with iron picket pins driven deep into the hard ground. Early in the march, the horses presented considerable challenges. Many were only half-broken and unaccustomed to military displays; the fluttering flags, rumbling wagons, pealing trumpets, and rattling sabers often startled them, leading to numerous wild stampedes across the prairie. Riders and arms were often left behind as the excited troop horses momentarily relished their liberty. Fortunately, no fatal accidents occurred, and all straying horses were eventually recovered.
Challenges on the Trail and the Pawnee Fork Junction
Records indicate a detachment of troops encamped on July 9 in what is now McPherson County, Kansas, where the trail intersected the Little Arkansas River. Here, the sheer ferocity of mosquitoes, gnats, and black flies drove both men and horses to distraction. Lieutenant-Colonel Ruff of the Missouri Volunteers, commanding this detachment, faced severe provision shortages. Aware of a loaded supply train ahead near Pawnee Fork, he dispatched a scout to halt it until his men could catch up. While awaiting the scout’s return, news arrived that Doniphan’s and Kearny’s men, following closely behind, were also experiencing starvation. To ensure prompt relief, Ruff sent additional couriers to overtake the wagon train. Tragically, one courier drowned while attempting to ford the Pawnee River, marking the first loss of life for the expedition on the Plains. His body was recovered and given a military burial. John Hughes, chronicler of Doniphan’s Expedition, vividly described the landscape as soldiers approached the river, highlighting the dramatic changes brought by subsequent settlement compared to its pristine state then:
“In approaching the Arkansas River, a landscape of the most imposing and picturesque nature makes its appearance. While the green, glossy undulations of the prairie to the right seem to spread out in infinite successions, like waves subsiding after a storm, and covered with herds of gamboling buffalo, on the left, towering to a height of 75 to a 100 feet, rise the sun-gilt summits of the sandhills, along the base of which winds the broad, majestic river, bespeckled with verdant isles, thickly beset with cottonwood timber, the sandhills resembling heaps of driven snow.”
On July 15, these disparate detachments successfully formed a junction at Pawnee Fork, within the modern-day limits of Larned, Kansas. The stream’s waters were so high that fording was impossible, necessitating the immediate construction of a makeshift bridge from cut cottonwood trees. Over these tree trunks, the army safely crossed, carrying the sick and all camp equipment. Horses were compelled to swim, while empty wagons were floated across and then laboriously hauled up the slippery bank by the soldiers. This arduous task required two days of incessant labor. Once across, the column pressed forward with renewed determination, the infantry trudging alongside the cavalry. The marching conditions, however, were brutal, causing feet to become terribly blistered and marking their passage with blood. This difficult journey was a critical part of Kearny’s campaign to secure the West.
Intelligence, Buffalo Charges, and Entering Mexican Territory
Two days later, somewhere along the Arkansas River, Major Howard rejoined the army. He had been dispatched to Santa Fe to assess the situation. Howard reported that while the common people of New Mexico seemed receptive to Kearny’s proposed terms of peace, the local officials remained hostile and were actively preparing to resist the American invasion. He claimed that 2,300 men were already under arms in Santa Fe, with another large force rapidly organizing at Taos. This startling intelligence was met with gallant cheers from the American soldiers, who, eager for a fight, pushed forward with new vigor.
The Cimarron crossing of the Arkansas River was reached on July 20, a day fraught with adventure. For the preceding 30 miles, the column had marched amidst vast herds of buffalo. Suddenly, a group of approximately 400 buffalo surged from a valley and charged headlong through the marching ranks. Chaos and confusion ensued, but the troops quickly rallied, launching a countercharge with guns, pistols, and drawn sabers. Many animals were killed, and the rest were driven helter-skelter across the Plains. Along the journey up the river, a few Mexican prisoners were taken but subsequently released. On July 29, the soldiers finally crossed the Arkansas River, establishing their first camp on Mexican soil about eight miles below Bent’s Fort. Here, strong guard lines were established to protect against both Mexican forces and Comanche Indians.
An unexpected adversary also emerged: during the night, prowling wolves stampeded the animals, causing over a thousand horses to break away from their guards and dash wildly across the prairie, further terrified by dangling lariats and pounding picket pins. Many were pursued for 30 to 50 miles before recapture, and nearly 100 horses were never recovered. While at this camp, several Arapaho chiefs visited and were hospitably entertained, showing particular awe at the American cannon.
Scouting Ahead and the Approach to Las Vegas
In anticipation of a general advance, Lieutenant de Courcy led a detachment of 20 men to scout towards Taos. During this mission, his party experienced a rather unusual incident involving the stubbornness of army mules, as related by the commander:
“We took three pack mules laden with provisions, and, as we did not expect to be long absent, the men took no extra clothing. Three days after we left the column, our mules fell, and neither gentle means nor the points of our sabers had the least effect on inducing them to rise. Their term of service with Uncle Sam was out. ‘What ‘s to be done?’ said the sergeant. ‘Dismount,’ said I. ‘Off with your shirts and drawers, men! Tie up the sleeves and legs, and each man bag one-twentieth part of the flour.’ Having done this, the bacon was also distributed to the men and tied to the cruppers of their saddles. Thus loaded, we pushed on without the slightest fear of our provision train being cut off.”
On August 2, the relatively small American army, with flags unfurled and in full military array, began its audacious advance into enemy territory. As it passed Bent’s Fort, the occupants proudly hoisted a large American flag, and the flat rooftops of the fort were crowded with eager spectators, including many Mexican and Indian women. The troops advanced steadily and without incident until they neared the Mexican town of Las Vegas. Here, scouts reported that the enemy was firmly entrenched in a mountain pass a few miles beyond the village, prepared to offer battle. The American soldiers were immediately deployed into battle formation and hurried forward, with the dragoons and St. Louis Mounted Volunteers leading the charge. Cartridges were distributed, cannons swabbed and readied, port fires set burning, and every rifle loaded. The men were palpably eager for a confrontation.
The Bloodless Occupation of Santa Fe and New Mexico
Yet, despite all these fervent preparations, the clash of arms never materialized. Las Vegas was entered without a single shot being fired. The village officials, instead of resisting, took an oath of allegiance to the United States, swearing upon the Cross. With barely a pause for this simple ceremony, the eager soldiers pressed straight on towards the canyon where they still hoped for battle. On August 16, near the village of San Jose on the Pecos River, three Mexican spies were captured. The most important of these, a son of General Salazar, was held prisoner, while the others were released. It was later discovered that these thoroughly frightened Mexicans had reported to their people that the invading American force numbered a staggering 5,000 strong, supported by an immense array of cannons.
Manuel Armijo, commanding the Mexican defenders, had by this time amassed 7,000 troops, most of whom were well-armed, and had occupied a strong defensive position in Apache Canyon. However, the exaggerated reports of the American invaders’ strength proved too daunting for Armijo and his men. This was despite his having sent a defiant note to General Kearny the day before, offering battle. It was around noon when the Americans reached the mouth of Apache Canyon, every man in the ranks keen to test the mettle of the Mexicans. Lieutenant W. H. Emory described the scene with anticipation:
“The sun shone with dazzling brightness; the guidons and colors of each squadron, regiment, and battalion were unfurled for the first time. The drooping horses seemed to take courage from the gay array. The trumpeters sounded ‘to horse’ with spirit, and the hills multiplied and reechoed the call. All wore the aspect of a gala day. About the middle of the day’s march, the two Pueblo Indians, previously sent to sound the chief men of that formidable tribe, were seen in the distance at full speed, with arms and legs both thumping the sides of their mules at every stride. Something was now surely in the wind. The smaller and foremost of the two dashed up to the general, his face radiant with joy, and exclaimed: ‘They are in the canyon, my brave; pluck up your courage and push them out.’”
However, much to the Americans’ surprise, the Mexican forces were nowhere to be found. The boastful Mexican army had already dissolved, plagued by internal quarrels and fear, and had fled to the mountains for safety, taking their commander with them. Another observer added, humorously:
“As we approached the ancient town of Pecos, a large fat fellow, mounted on a mule, came toward us at full speed and, extending his hand to the general, congratulated him on the arrival of himself and his army. He said, with a roar of laughter, ‘Armijo and his troops have gone to hell, and the canyon is all clear.’”
Conclusion: A Swift and Strategic Victory
Thus, the Conquest of New Mexico was achieved with remarkable ease and virtually no bloodshed, effectively sweeping away centuries of Spanish influence on the Great Plains forever. The primary waves of the Mexican-American War on the Plains then shifted further south and west, beyond this immediate region. With Armijo’s flight from the country, New Mexico became the undisputed property of the United States. While Doniphan’s forces endured hardships in the mountains and Kearny continued his significant march across Arizona to California, the critical phase of securing New Mexico was swiftly concluded, a testament to strategic military presence and a touch of psychological warfare through exaggerated numbers. This bloodless victory remains a pivotal moment in American westward expansion, demonstrating the strategic prowess that shaped the nation’s borders.
