James K. Polk may have been virtually unknown, but he assumed the presidency with a clearly defined set of goals: to reduce the tariff, reestablish the independent Treasury system, settle the dispute over ownership of Oregon, and bring California into the Union. Congress soon enacted the first two goals, and the third was accomplished in an agreement with Great Britain dividing Oregon at the forty-ninth parallel. Many northerners were bitterly disappointed by this compromise, considering it a betrayal of Polk’s campaign promise not to give up any part of Oregon without a fight. But the president secured his main objectives, the Willamette Valley and the magnificent harbor of Puget Sound.

Acquiring California proved more difficult. Polk dispatched an emissary to Mexico offering to purchase the region, but the Mexican government refused to negotiate. By the spring of 1846, Polk was planning for military action. In April, American soldiers under Zachary Taylor moved into the region between the Nueces River and the Rio Grande, land claimed by both countries on the disputed border between Texas and Mexico. This action made conflict with Mexican forces inevitable. When fighting broke out, Polk claimed that the Mexicans had “shed blood upon American soil” and called for a declaration of war.

War News from Mexico, an 1848 painting by Richard C. Woodville, shows how Americans received war news through the popular press.

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