Sometimes, politics impacts the course of military action.

As General Zachary Taylor’s forces had gained victories over Mexico at Palo Alto, Resaca de la Palma, and Monterrey in the late summer of 1846, his popularity rocketed, aided by newspaper stories back home of his “Rough and Ready” maneuvers that had ensured success. James K. Polk, sensitive to his role as commander-in-chief, responded by dividing Taylor’s forces and sending General Winfield Scott to take command of additional forces and invade central Mexico. Taylor responded in kind by strategically deploying his remaining 5,000 troops against Santa Anna’s 15,000 at Buena Vista in an unexpected but fiercely fought victory. The Whigs celebrated by touting Taylor’s name for the next presidential election. Polk was simultaneously elated and frustrated.

The two generals and the president seemed to be using the conflict for more than just affirming Texas independence and land acquisition.

Scott’s name headlined the newspapers — as it had for more than 30 years of military service — when he plotted a unique maneuver, an amphibious landing at Veracruz less than a month later. Always willing to take chances and move troops accordingly, he pushed forward, and during the next five months, his forces covered 200 miles until Mexico City was in sight. Newspaper reporters doubted his chance of victory. He was outnumbered more than three to one, and supplies were limited due to the unknown terrain. His forces included numerous Southerners who knew how to shoot and could endure the hard constraints of the action, but they had little experience as part of an organized fighting force.

But fight they did, and by September 1847, General Winfield Scott, “Old Fuss and Feathers,” held Mexico City.

Negotiations began with a new Mexican government since General Santa Anna had once again been “removed” from power. Nicholas Trist, often negotiating with his own goals instead of the president’s directions, ultimately drafted the Treaty of Guadalupe Hidalgo, agreeing that the United States would pay $15 million for California and New Mexico, and the southern border of Texas would be the Rio Grande. Polk sent the treaty to the U.S. Senate, and approval was granted 38-14 on March 10, 1848. Interestingly, the “Nay” votes were divided between Democrats who wanted more territorial concessions and Whigs who disdained any additional lands that would potentially upset the balance in Congress between slave-holding and non-slave-holding states.

By the end of his one term, President James K. Polk had fulfilled the goal of manifest destiny by creating a United States that stretched from “sea to shining sea.”

But there was more work to be done.

There was the Oregon question. Polk had campaigned in 1844 on settling the northern boundary issue. Building on his concept of U.S. control of Oregon based on the early explorations during Thomas Jefferson’s administration and the fact that the U.S. and Britain had jointly occupied the territory for decades, he pushed for a resolution of the ownership question. While he allowed advocates to proclaim “54-40 or Fight” as a demonstration of U.S. will, Polk was bluffing. The compromise gave the United States exactly what Polk had been visualizing — the 49th parallel as our northern boundary in the west. When the ink dried, the United States now had control of the Columbia River and the present-day states of Oregon, Idaho, and Washington. The president celebrated quietly at home with his lovely wife and political ally, Sarah Childress Polk.

Polk had one foreign-policy goal remaining — a presence in Central America that would guarantee U.S. security. As the former speaker of the House, Polk understood the precarious balance of power and influence that had shifted in Central and South America during the early 19th century, witnessing decades of revolutions. When New Granada (Colombia) contacted the U.S. in the hope of securing a trade agreement, Polk saw an opportunity. The agreement, signed by U.S. Minister Benjamin A. Bidlack, gave the U.S. a “right of way” across the Isthmus of Panama in exchange for guaranteeing that the isthmus would remain neutral and that New Granada would have sovereignty. While the agreement did not garner much public attention at the time, it became the basis for the eventual construction of the Panama Canal. Polk’s long-range vision would be fulfilled in 1914 when the two oceans would be connected, and the U.S.‘s influence in the region would build upon his and Teddy Roosevelt’s goals on influence.

But what about the home front? Next week, friends.