306 Chapter 11 Westward Expansion
Polk then ordered General Zachary Taylor into
Texas to defend the border. However, the location of
that border was in dispute. Texas claimed the Rio
Grande; Mexico insisted that the boundary was the
Nueces River, which emptied into the Gulf of Mexico
about 150 miles to the north. Taylor reached the
Nueces in July 1845 with about 1,500 troops and
crossed into the disputed territory. He stopped on the
southern bank at Corpus Christi, not wishing to pro-
voke the Mexicans by marching to the Rio Grande.
In November, Polk sent an envoy, John Slidell,
on a secret mission to Mexico to try to obtain the dis-
puted territory by negotiation. He authorized Slidell
to cancel the Mexican debt in return for recognition
of the annexation of Texas and acceptance of the Rio
Grande boundary. The president also empowered
Slidell to offer as much as $30 million if Mexico
would sell the United States all or part of New
Mexico and California.
It would probably have been to Mexico’s advan-
tage, at least in the short run, to have made a deal
with Slidell. The area Polk wanted, lying in the path
of American expansion, was likely to be engulfed as
Texas had been, without regard for the actions of the
American or Mexican governments. But the Mexican
government refused to receive Slidell. Amid a wave of
anti-American feeling, a military coup occurred and
General Mariano Paredes, the new head of state,
promptly reaffirmed his country’s claim to all of
Texas. Slidell returned to Washington convinced that
the Mexicans would not give an inch until they had
been “chastised.”
Polk had already ordered Taylor to advance to the
Rio Grande. By late March 1846 the army, which
swelled to about 4,000, had taken up positions near the
Mexican town of Matamoros. The Mexicans crossed the
river on April 25 and attacked an American mounted
patrol. They were driven back easily, but when news of
the fighting reached Washington, Polk asked Congress
to declare war. He treated the matter as a fait accompli:
“War exists,” he stated flatly. Congress accepted this rea-
soning and without actually declaring war voted to raise
and supply an additional 50,000 troops.
From the first battle, the outcome of the Mexican
War was never in doubt. At Palo Alto, north of the Rio
Grande, 2,300 Americans scattered a Mexican force
more than twice their number. Then, hotly pursuing,
1,700 Americans routed 7,500 Mexicans at Resaca de
la Palma near what is now Brownsville, Texas. Fewer
than 50 U.S. soldiers lost their lives in these engage-
ments, while Mexican losses in killed, wounded, and
captured exceeded 1,000. Within a week of the out-
break of hostilities, the Mexicans had been driven
across the Rio Grande and General Taylor had his
troops firmly established on the southern bank.
The Mexican army was poorly equipped and,
despite a surfeit of high-ranking officers, poorly led.
The well-supplied American forces had a hard core of
youthful West Pointers eager to make their reputa-
tions and regulars trained in Indian warfare to pro-
vide the leadership needed to turn volunteer soldiers
into first-rate fighting men. Yet Mexico was a large,
rugged country with few decent roads; conquering it
proved to be a formidable task.To the Halls of Montezuma
President Polk insisted not only on directing grand
strategy (he displayed real ability as a military planner)
but on supervising hundreds of petty details, down to
the purchase of mules and the promotion of enlisted
men. But he allowed party considerations to control
his choice of generals. This partisanship caused
unnecessary turmoil in army ranks. He wanted, as
Thomas Hart Benton said, “a small war, just large
enough to require a treaty of peace, and not large
enough to make military reputations dangerous for
the presidency.”
Unfortunately for Polk, both Taylor and Winfield
Scott, the commanding general in Washington, were
Whigs. Polk, who tended to suspect the motives of
anyone who disagreed with him, feared that one or
the other would make political capital of his popular-
ity as a military leader. The examples of his hero,
Jackson, and of General Harrison loomed large in
Polk’s thinking.
Polk’s attitude was narrow, almost unpatriotic,
but not unrealistic. Zachary Taylor was not a bril-
liant soldier. He had joined the army in 1808 and
made it his whole life. He cared so little for politicsAmerican soldiers—some of them regulars in deep blue uniforms,
others in buckskin cowboy outfits—fight in the streets to drive
Mexicans from a Spanish mission in Monterrey, California, in 1846.