James Knox Polk (November 2, 1795 – June 15, 1849) was the 11th president of the United States, serving from 1845 to 1849. He previously was Speaker of the House of Representatives (1835–1839) and governor of Tennessee (1839–1841). Taylor and Commodore David Conner of the U.S. Navy, commanding American ships off the Mexican coast, were both ordered to avoid provoking a war, while preparing for conflict, and to respond to any Mexican aggression. Sending the U.S. Army there was a provocative act. Although Polk had the military prepare for war, he did not believe it would come to that; he thought Mexico would give in under duress, which proved to be a significant miscalculation. In March 1847, Polk learned that Taylor had continued to march south, capturing the northern Mexican town of Saltillo. Continuing beyond Saltillo, Taylor's army fought a larger Mexican force, led by Santa Anna, in the Battle of Buena Vista.