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The main disagreement between the United States and Mexico in 1846, when the war began, was the boundary of Texas. The state was just annexed to the chagrin of the Mexicans, who had lost it in 1836 to independence. Mexico had the boundary at the Nueces River, but the Americans believed Texas should stop at the Rio Grande, to the south. In 1846, President James Knox Polk ordered General Zachary Taylor into the disputed territory between the two rivers, and the Mexicans crossed over to engage them. This gave Polk the excuse he needed to ask Congress for a declaration of war.

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13y ago

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