This collection consists of John Crockett's bound, handwritten diary from his time in the Mexican-American War. Crockett's diary entries begin on June 10, 1846, the date Crockett mustered into the U.S. Army Cavalry by General Brazelton in Knoxville. His unit then marched through Tennessee to Memphis, took the steamboat “Sea Bird" to New Orleans, then traveled on to Galveston, Texas, marching through Corpus Christi to Brownsville and then Matamoros, Mexico. After marching to Victoria, Mexico from Matamoros, Crockett was detailed to take an exchange from General Zachary Taylor to General Winfield Scott. Crockett's near-daily diary entries end on January 21, 1847.

At the back of Crockett's diary is a four-page list of correspondents with whom Crockett was in touch during 1846.