Two Armies on the Rio Grande: The First Campaign of the US-Mexican War

Two Armies on the Rio Grande: The First Campaign of the US-Mexican War

Two Armies on the Rio Grande: The First Campaign of the US-Mexican War

Two Armies on the Rio Grande: The First Campaign of the US-Mexican War


The opening campaign of the US-Mexican War transformed the map of each nation and shaped the course of conflict.

Armed with a broad range of Mexican military documents and previously unknown US sources, Douglas Murphy provides the first balanced view of early battles such as Palo Alto and Resaca de la Palma. He reassesses previously covered territory and also poses new questions.

Why did Mexico establish its defenses south of the Rio Grande while claiming territory north of the river? What was Mexico's strategy in the campaign against the United States? What factors most affected Mexico's defeat?

In confronting these questions, Murphy shows that the campaign was a complex chess match with undercurrents of political intrigue, economic motivations, and personal animosities as much as military action. Two Armies on the Rio Grande will transform our understanding of the US-Mexican War.


On May 18, 1846, two very different scenes unfolded near the Mexican city of Matamoros. To the southwest of town, Mexican troops were on the road after abandoning their barracks in the dark of night. Leaving behind hundreds of wounded compatriots who could not make the march, weary and demoralized men trudged toward the Sierra Madre and the distant city of Monterrey. Meanwhile, to the north, on the banks of the Rio Grande, a small, spontaneous ceremony unfolded. Thousands of American soldiers stood at water’s edge on the north shore, watching a small group of their countrymen slowly hoist the Stars and Stripes over an abandoned Mexican fort. As the banner reached the top of its staff and unfurled in the breeze, the troops erupted in cheers, and military bands began to play, shattering the morning silence. With forlorn resignation on one side of town and joyous celebration on the other, Matamoros had fallen, and the first campaign of the war between the United States and Mexico came to a close.

Perspectives on the events that led up to this moment also diverged widely, with attitudes largely dependent upon whether the observer identified with the troops on the north side of the city or those to the south. Soldiers of the US Army focused on their successes in the recent battles of Palo Alto (May 8) and Resaca de la Palma (May 9) and the utter decimation of the Mexican forces arrayed against them. “They are really glorious victories,” Lt. Nathaniel Wyche Hunter wrote of the two encounters, “and I have no doubt that they will be appreciated as such by the Country at large.” The American press agreed. “The battles of Palo Alto and Resaca de la Palma,” proclaimed the Charleston, South Carolina Mercury, for example, “are destined to occupy a page in history never to be effaced.” Mexicans focused instead on the disastrous effects of these clashes, most notably the raising of the enemy flag over the frontier city of Matamoros. The Gaceta de Tamaulipas presented that act as the crowning shame of “ten days of sorrowful memory” and called failure on the Rio Grande “a transcendent event that threatens the most important interests of the nation, its respect, and its dignity.” The Mexico City newspaper El Monitor Republicano offered more measured but equally earnest wording, referring to lost battles and the surrender of a city as “a terrible shift of capricious fortune.”

These conflicting sentiments quickly found their way into the first chronicles of the military campaign. In the United States, authors rushed to celebrate victory in . . .

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