James K. Polk was the 11th President of the United States, serving from 1845 to 1849. He was a strong leader who accomplished a great deal during his time in office, including the annexation of Texas and the acquisition of California and Nevada through the Mexican-American War. Polk was also a skilled diplomat who negotiated several important treaties, including the Webster-Ashburton Treaty with Great Britain. Despite his many accomplishments, Polk's presidency was cut short by his untimely death in 1849, just a few months after the end of the Mexican-American War. Overall, James K. Polk was a significant figure in American history who played a key role in shaping the country's expansion and growth during the 19th century.