The Mexican-American War on the Plains

By Randall Parrish in 1907

Army Train on the Santa Fe Trail

Army Train

In April 1846, Mexico declared war against the United States, and a month later President James Polk called into the field 50,000 volunteers. General Stephen W. Kearny was given command of the army intended for action in the West, and this force was divided into three separate commands. The first, led by himself, was destined to the Pacific coast; a thousand volunteers, under Colonel Alexander W. Doniphan were to descend upon Chihuahua; while the third division, commanded by Sterling Price, was expected to garrison Santa Fe and retain control of New Mexico.

In this connection, Colonel Henry Inman recorded an interesting story of the Plains, as follows:

“Early in the Spring of 1846, before it was known, or even conjectured, that a state of war would be declared, a caravan of twenty-nine traders, on their way from Independence to Santa Fe, beheld, just after a storm, and a little before sunset, a perfect, distinct image of the Bird of Liberty, the American eagle, on the disc of the sun. When they saw it, they simultaneously and almost involuntarily exclaimed that in less than twelve months the Eagle of Liberty would spread his broad plumes over the Plains of the West and that the flag of our country would wave over the cities of New Mexico and Chihuahua.”

The value of this vision and the truth of its fulfillment can be left to the judgment of the reader.

General Kearny’s army moved out onto the prairie from Fort Leavenworth, Kansas in detached columns, during the Summer of 1846, and took up its long march through the wilderness. It consisted of two batteries of Artillery, three squadrons of First U. S. Dragoons, the First Regiment of Missouri Cavalry, two companies of infantry, and a detachment of Topographical Engineers. By August this force was concentrated in camp on the old Santa Fe Trail, about nine miles below Bent’s Fort, Colorado on the Arkansas River. The incidents and adventures of this march over the Plains have been recorded in detail by the commandant of the Engineers, Lieutenant W. H. Emory, and John T. Hughes of the Missouri Cavalry.

At the first planning of this expedition, it was gravely questioned by officials whether so large a body of troops could be marched such a distance over an uninhabited waste, having no base of supplies, and totally severed from all possibility of reinforcement. It was considered an experiment, and a dangerous one, yet an immense amount of provisions was carried in huge wagons, carefully guarded, and beef cattle were driven the entire distance. These subsisted entirely by grazing on the nutritious buffalo grass bordering the trail. At night it was the custom to confine them in a corral formed by the wagons, although occasionally they were tethered to an iron picket-pin driven 15 inches into the hard ground. At the outset of the march, the horses made considerable trouble. Many of them being only half broken and unused to military display, the fluttering flags, the rumbling of wagons, the pealing trumpets, and the rattling sabers proved too much for their nerves, and there were numerous wild stampedes, the frightened animals scampering pell-mell across the prairie. Rider and arms left behind, the excited troop-horse enjoyed to the full his liberty. No fatal accidents occurred, however, and the straying horses were all eventually recovered.

The troops marched in separate bodies. We have a record of such a detachment going into camp on the 9th of July, in what is now McPherson County, Kansas, where the trail crossed the Little Arkansas River. The mosquitoes, gnats, and black flies were so fierce as to drive men and horses frantic. Lieutenant-Colonel Ruff of the Missouri Volunteers was in command, and his men were very short of provisions. Knowing a loaded train was ahead near Pawnee Fork, he had sent a scout forward to halt it until he could come up.

Arkansas River Camp

Arkansas River Camp

While he waited for this scout to return, word reached him that Doniphan’s and Kearny’s men, just behind him, were also in a starving condition. To make sure of early relief he sent other couriers hastily forward to overhaul the wagon train, and one of them, attempting to ford the fork of the Pawnee River, was drowned. His body was recovered and given a military burial. This was the first loss that occurred to the expedition on the Plains. John Hughes, the author of Doniphan’s Expedition, wrote thus of the scene presenting itself as the soldiers approached the river. Comparing its appearance then with its appearance now, the great change wrought by settlement can be clearly realized.

“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 succession, like waves subsiding after a storm, and covered with herds of gamboling buffalo, on the left, towering to a height of seventy-five to a hundred 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.”

It was on July 15th that these separate detachments formed a junction at Pawnee Fork, within the limits of what is now the city of Larned, Kansas. The waters of the stream were so high that fording was impossible, and the soldiers were immediately employed in cutting down cottonwoods and building a rude bridge. Over the tree trunks the army passed safe to the other shore, bearing in their arms the sick, and all the equipment of the camp. The horses were compelled to swim, while the empty wagons were floated across, and hauled up the slippery bank by tugging soldiers. This required the incessant labor of two days; and then the little column pressed resolutely forward, the infantry plodding along beside the cavalry, although the marching feet became terribly blistered, marking their passage with blood. Two days later, somewhere along the Arkansas River, Major Howard, an officer who had been sent forward to Santa Fe to learn the situation, rejoined them. His report was that the common people of New Mexico favored the conditions of peace proposed by Kearny, but that the officials were hostile and making active preparations to resist invasion. Two thousand three hundred men, he said, were already under arms in Santa Fe, while another large force was being rapidly organized at Taos. The little army of Americans received this startling news with gallant cheers, and pushed forward with new vigor, eagerly hoping for a fight.

Bent's Fort, Colorado by Kathy Alexander.

Bent’s Fort, Colorado by Kathy Alexander.

The Cimarron crossing of the Arkansas River was reached on the twentieth. It was a day of adventure. During the last thirty miles, the column had been in the midst of great herds of buffalo. Suddenly a bunch of about four hundred swept up from out the valley and charged headlong through the marching ranks. Instantly all was turmoil and confusion, but the troops rallied, made a countercharge, using guns, pistols, even drawn sabers, killing many of the animals, and driving the remainder helter-skelter over the Plains. On the way up the river a few Mexican prisoners were taken, but subsequently released, and, on the twenty-ninth, the soldiers finally crossed the Arkansas River and made their first camp on Mexican soil about eight miles below Bent’s Fort. Here they established strong guard lines in protection against both Mexicans and Comanche Indians.

But, they had an unexpected enemy to cope with. During the night prowling wolves stampeded the animals, and more than a thousand horses broke away from their guards and dashed madly over the prairie, frightened yet more by dangling lariats and pounding picket-pins. Many were followed for thirty to fifty miles before they were recaptured, and nearly a hundred were never recovered. While at this camp several chiefs of the Arapaho appeared and were hospitably entertained. They were especially impressed by the cannon.

In preparation for a general advance, twenty men, under Lieutenant de Courcy, were sent forward to scout in the direction of Taos. While on this trip the little party had an unusual experience with the obstinacy of the army mule since related by the commander. He said:

“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 down, and neither gentle means nor the points of our sabers had the least effect in 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 distributed to the men also and tied to the cruppers of their saddles. Thus loaded we pushed on, without the slightest fear of our provision train being cut off.”

The little army, with flags flying and everything in military array, began its bold advance into the enemy’s country on August 2nd. While it was passing Bent’s Fort, the occupants ran up a large American flag, and the flat tops of the houses were densely crowded with interested spectators. Among them were many Mexican girls and Indian women. The troops advanced steadily without alarm until they approached the Mexican town of Las Vegas. Here, scouts reported the enemy as being strongly entrenched in a mountain pass a few miles beyond the village, where they proposed giving battle. The soldiers were at once thrown into battle line and hurried forward, the dragoons and St. Louis Mounted Volunteers in the lead. Cartridges were distributed, the cannon swabbed and rigged, the port fires set burning, and every rifle loaded. The men were eager for the clash of arms. Yet all these preparations were in vain. Las Vegas was entered without the firing of a shot, and the officials of the village took an oath of allegiance to the United States, swearing upon the Cross instead of the Bible. Hardly delaying long enough for this simple ceremony, the eager soldiers swept straight on toward that canyon where they yet hoped for the grapple of arms. On August 16, on the Pecos River, near the village of San Jose, three Mexican spies were captured. The most important of these, a son of General Salezar, was held prisoner, but the others were released. It was learned later that these thoroughly frightened Mexicans had reported to their own people that the invading force was 5,000 strong, with an immense number of cannons.

Stephen Watts Kearney

Stephen Watts Kearney

Manuel Armijo, in command of the Mexican defenders, had by this time, assembled 7,000 troops, most of them well armed, and occupied a strong position in Apache Canyon. But, this news of the numbers of the invaders was too much for him and his men, although the day previous he had written a defiant note to General Kearny offering battle. It was about noon when the Americans reached the mouth of the canyon, every man in the ranks eager to try the mettle of the Mexicans. Lieutenant W. H. Emory described the scene:

“The sun shone with dazzling brightness; the guidons and colors of each squadron, regiment, and battalion were for the first time unfurled. 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.'”

But, they were not there; already the boasting Mexican army had faded away; rent by quarrels and fear, and bearing their commander with them, all had fled to the mountains for safety. Another added:

“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 army. He said, with a roar of laughter, ‘Armijo and his troops have gone to hell, and the canyon is all clear.”

Thus easily was New Mexico won without bloodshed, and the centuries-long Spanish influence on the Great Plains swept away forever. The waves of war passed on to the south and west beyond the limits of this region. With Doniphan’s hardships and sufferings in the mountains, and Kearny’s wonderful march across Arizona to California, there was nothing to do. When Armijo fled from the country it became the undisputed property of the United States, and the conquest of New Mexico was practically ended.


Compiled and edited by Kathy Weiser/Legends of America, updated October 2020.

About the Author: This article was written by Randall Parrish as a chapter of his book, The Great Plains: The Romance of Western American Exploration, Warfare, and Settlement, 1527-1870; published by A.C. McClurg & Co. in Chicago, 1907. Parrish also wrote several other books including When Wilderness Was King, My Lady of the North, Historic Illinois, and others. The text as it appears here; however, is not verbatim as it has been edited for clarity and ease of the modern reader.

Also See:

The Mexican-American War

Mexican-American War Timeline

Wars, Military, & Soldiers

Westward Expansion and Manifest Destiny