The Nathaniel Wilson Leighton Papers consist of diaries, correspondence, memorabilia, and biographical information. The material primarily relates to his work as a surgeon during the United States Civil War from 1861-1864. He was a member of the Seventy-second Regiment of the New York Volunteers, and then was transferred to the One Hundred and Seventy-third Regiment. His earlier diaries primarily discuss the weather and his desire to go home and be with his wife. As the time goes on and Leighton's regiment enters combat his diaries become considerably more detailed. They describe the movement of the regiments, battles, and medical issues he had to deal with. The correspondence, primarily letters between Leighton and his wife, provides information about the Civil War but more closely documents the relationship between the two. Leighton frequently expresses his desire to return home and offers advice for the care of their daughter, who was born while he was with his regiment. Leighton's wife, Mary Elizabeth "Lizzie" Purinton, also expresses her desire to be with her husband and offers him details about their child's progress. The papers also contain a significant amount of memorabilia relating to his service in the United States Civil War, including insignia, a note regarding resolutions passed upon Leighton's resignation, recommendations for Leighton to be accepted as a medical volunteer, and other documents. Of note is "An Alphabetical List of the Battles of the War of the Rebellion," in which Leighton marked numerous battles that he participated in. These battles include the Second Battle of Bull Run, Virginia (August 30, 1862), Manassas, Virginia (November 5, 1862), and the Siege of Port Hudson, Louisiana (May 27 to July 9, 1863), among others. Several photographs of Leighton along with a number of photographs and other images of battlegrounds are included in the collection.