Following graduation from Amherst, Horace Maynard joined the faculty of the university (then East Tennessee College) in 1838 as a tutor in the Preparatory Department. He was appointed principal of the Preparatory Department in 1840 and became teacher of mathematics and ancient languages in 1841.
Maynard studied law while on the faculty and was admitted to the bar in 1844. One of his famous cases involved a bitter dispute between Knox County and proponents of the establishment of Union County from a portion of Knox County, in which Maynard represented the Union County interests. In gratitude for his successful representation, Union County residents named the county seat Maynardville. He was elected to Congress in 1857, 1859, and 1861.
Maynard traveled through Tennessee after Abraham Lincoln was elected president in an effort to keep Tennessee from seceding from the Union and took his seat in Congress after Tennessee seceded from the Union. In 1863 Andrew Johnson, who also continued to serve in Congress—as a senator after Tennessee seceded, and then he was appointed military governor of the state by Abraham Lincoln—appointed Horace Maynard attorney general of Tennessee.
In 1865 Maynard was elected to Congress to represent the Second Congressional District and was instrumental in having a special congressional act passed to allow Tennessee to receive the benefits of the 1862 Morrill Act. He served in Congress until 1875, when President Ulysses S. Grant appointed him minister to Turkey. In 1880 President Rutherford B. Hays recalled Maynard and appointed him to the cabinet position of postmaster general, a position he held until March 1881. He became a trustee of the university in 1865, and his papers are in UT Libraries’ Special Collections.