In 1808 he received his first commission as an officer, he was in charge of Fort Pickering, (now Memphis). He moved from one frontier post to another, which built his professional reputation. Taylor was not defeated despite alarming odds in a battle against the Mexican general Santa Anna at Buena Vista. When the battle was over, Taylor's army of 6,000 had defeated a Mexican force of 20,000, and Zachary Taylor, "Old Rough and Ready," as he was known because of his attitude in sharing his troops' hardships, was a national hero. In his zeal for command the young officer became the first brevet major in the U. S. Army. He was also known for his fierce fighting the Seminole Indians in Florida Territory from 1837 to 1840. A belief of his was that the president should stand above party politics. Taylor would not except any postage due correspondences. Because of this, he did not receive notification of his nomination for president until several days later.

Taylor never had time to list an offical place of residence and never took the time registered to vote not even in his own election. Taylor was prepared to keep the Union together force rather than by compromise. As a slave owner he lured southern votes and his military activities would appeal to northerners. He held property and slaves in a few southern states including Louisiana, Kentucky, and Mississippi. He was a family man that deeply loved his invalid wife, his children, and grandchildren, Taylor valued family life and played host to countless relatives. Because of his military record Zachary Taylor was the most popular man in America, a hero of the Mexican-American War. On July 4, 1850, after attending celebrations in Washington, Taylor came down with a serious stomach ailment. He died on July 9, and more than 100,000 people lined the funeral route to see the hero laid to rest.