James K. Polk was not a man given to frivolity on his birthday. When he turned fifty-three on November 2, 1848, the eleventh president of the United States reflected gloomily in his diary. “I am solemnly impressed with the vanity and emptiness of worldly honours and worldly enjoyments,” he wrote, “and of the wisdom of preparing for a future estate.” After brooding over his waning time on earth and on the impending end of his term in office, Polk noted that he had spent the day, as he had spent so many others, “busily occupied in my office.”

Much as Polk ignored the occasion in favor of carrying out his administrative duties, most Americans will neglect to observe the 220th anniversary of Polk’s birth this week. There will be no presidential speeches in his honor, no parades, and no celebratory dinners, because in the popular imagination Polk has largely faded from memory. Indeed, Polk’s fame has faded to such an extent that only 17% Americans recently asked to rank past presidents based on “memorability” could even identify Polk as a president, let alone describe what he accomplished in his term in office. This placed Polk’s “memorability” somewhere between James Garfield and Warren G. Harding, two presidents most famous for dying while in office. Unlike those presidents, however, Polk left behind a slew of legislative accomplishments and a deeply fraught and complicated legacy.

In 1844, James Polk, then a little-known congressman from Tennessee, somewhat surprisingly won the nomination of the Democratic Party, and promised that given the divisions within the party and his relatively young age of forty-nine, he would only serve a single term in the White House if elected. Upon winning a closely contested national election against Whig candidate Henry Clay, Polk became the youngest man to hold the office of the presidency to that point in American history. But Polk’s relative youth and inexperience did not prevent him from fulfilling his presidential goals. He settled a festering boundary dispute with Great Britain over the Oregon Territory, secured passage of the Walker Tariff that amounted to a major reform, and helped establish the independent treasury system that lasted into the twentieth century. Polk’s most enduring accomplishment, however, was the waging of war against Mexico and signing the stunning treaty that marked its conclusion.

When running for office, Polk had pledged to annex Texas – which had broken away from Mexico nearly a decade before – to the United States at the earliest possible moment. His attempt to bring Texas into the Union promptly led to a boundary dispute with Mexico, a conflict that escalated into warfare when Polk ordered American troops into the disputed region. Polk then demonstrated himself an aggressive commander-in-chief, ordering a full-scale invasion of Mexico that ultimately led to the capture of Mexico City and demanding at the conclusion of the war more than a mere boundary adjustment. In February of 1848, the United States effectively imposed upon Mexico the Treaty of Guadalupe Hidalgo, which added an additional 525,000 square miles to the United States and stripped Mexico of nearly half of its territory. Between this acquisition and the territory added by resolving the dispute over the Oregon Territory, Polk added over one million square miles to the United States, more than any other single president before or since.

Despite reforming the tariff and the treasury and expanding the nation’s reach to the Pacific Ocean, Polk’s legacy is hardly an unambiguous triumph. Surely one reason that Polk has faded from the popular historical memory is that Americans tend to downplay events from our past that do not reflect the nation in the most positive light. We often forget the imperialist impulse that helped produce the war with Mexico, the fact that the growth of the United States into a continental power came directly at the expense of other nations, and that it was immigrants pouring into the Mexico from the United States rather than the reverse that caused the borders to shift and triggered a war. Simply put, Polk’s legacy can be difficult to assess because unlike a Washington, a Lincoln, or a Roosevelt, the chief accomplishment of his administration is one that cannot be remembered without acknowledging important moral questions.

Perhaps the most realistic way to remember James Polk on the 220th anniversary of his birth is to see him as representative of the tumultuous decade of the 1840s. Polk has sometimes been portrayed, both in his time and since, as a Machiavellian manipulator who engineered the Mexican-American War to cement his own place in history. But throughout his term in office, Polk remained constrained and limited by the powers granted to him. It is hard to blame Polk for the Mexican-American war, or for the blatant land grab at its conclusion, without noting that the American people voted for him in 1844, asked for the annexation of Texas, and generally supported the war when it erupted. We might fault Polk for using whatever means he deemed necessary to achieve the goals that he set for himself from the very beginning of his term, but he himself simply believed that he was carrying out the will of the American people. Whatever one believes about Polk, however, he deserves at the very least to be remembered. Arguably, no one-term president ever accomplished as much as he did.