[fortheDeclaration]

During and after the war, many in the United States placed the majority of the blame for the Mexican-American War squarely on the shoulders of Mexico. There may be a grain of truth in this ultra-patriotic view (Combs 99). President Polk sent troops under General Zachary Taylor to the region between the Rio Grande and Nueces Rivers. Texas believed that its southern boundary was represented by the Rio Grande River. The Mexicans, however, did not acknowledge this boundary and instead believed that it was the Nueces River. So, the Americans believed they were on Texan (soon to be American) soil, while the Mexicans believed that the Americans were on Mexican soil (Lavender 130). When Mexican forces attacked the Americans in this region, Polk believed that Mexico "invaded our territory, and shed American blood upon the American soil" (Richardson 442). With this information in hand, Polk proceeded to ask the Congress for a declaration of war, which he received easily. However, according to Polk's diary and other sources, he planned to ask Congress for a declaration before word of the Mexican "attack" ever reached Washington (Quaife 386). Refuting this "Mexico's Fault" theory even more is the fact that the government of Mexico at this time was in a period of chaos (Garraty and Gay 811). Still, the attack proved an effective scapegoat for not only Polk, but many other pro-war politicians. The Mexicans can not be totally blamed for this war. The attack that many patriots were so fond of using as justification for the war was simply an attempt by Mexico to defend land that it believed belonged to Mexico. Of course, Mexico could have responded in a more peaceful manner to the idea of Texas annexation. And Mexico could have responded better to American desires to purchase California and other areas of the Southwest (Lavender 130). If only it could be as easy as the Louisiana Purchase had been, Polk must have thought.

[GOPcapitalist]

The Mexicans, however, did not acknowledge this boundary and instead believed that it was the Nueces River. So, the Americans believed they were on Texan (soon to be American) soil, while the Mexicans believed that the Americans were on Mexican soil (Lavender 130).

Actually, Mexico had previously defined the Rio Grande as the boundary of Texas. Article IV of the 2nd Treaty of Velasco:

A treaty of Commerce, Amity and limits will be established between Mexico and Texas. The territory of the latter not to extend beyond the Rio. Bravo del Norte.

Signed:
David G. Burnet, President of the Republic of Texas
Antonio Lopez de Santa Anna, President of Mexico
May 14, 1836

Mexico later reneged on both that clause establishing the border and its promise to recognize Texas independence all together and from 1837 to 1845 made several unsuccessful attempts to invade and reconquer Texas. Meanwhile Texas established its own government and obtained foreign recognition of its sovereignty and boundaries from the United States and all the major European powers. What Mexico was now asserting as its "border" in 1846 after a decade of violating that border and every other was of no merit by that point.