This collection contains over 4,000 letters to Dr. Gustavus Richard Brown Horner (from family members and colleagues as well as a letterbook containing copies of letters from Dr. Horner in Warrenton, Virginia, and Philadelphia, Pennsylvania from 1824 to 1892. (The collection totals 41 document boxes).

The letters chronicle the historical and political events of the time including enslavery, violence against indigenous persons, the Civil War, post war conditions, westward expansion, political elections, banking and business failures, difficulties of farming wheat and other crops, the emergence of railroads, operating an academy, education, and differences between professional and agricultural life in the nineteenth century. In addition to enslavery and the Civil War, there are descriptions of other major historical events including General Lafayette at George Washington's gravesite, a sketch of Abraham Lincon's hearse, Nat Turners rebellion, and the loss of many family members to Cholera, Scarlet Fever, and other ailments of the time.

Series 4 Enslavery and African Americans (Content Warning:This material contains references or imagery involving racism. The purpose of this note is to give users the opportunity to decide whether they need or want to view these materials, or at least, to mentally or emotionally prepare themselves to view the materials.)There are letters about an enslaved person named Stanton Butler. Of note is a description of seven white men lynching an African American, named Arthur Gordon Jordan in Winchester, Virginia on January 19, 1880. In addition to the description is a sketch of the lynching.(Box 36 Volume 10)

Also included are indentures, receipts, newspapers, school notebooks, artwork, and diaries (journals) about Horner's medical and naval career, including his expeditions around the world (fighting piracy) as a Navy Ship surgeon, including South America (Rio de Janeiro, Brazil and Uruquay) the Mediterranean including Italy, Sicily, and Greece. He specifically mentions his voyages on the USS Macedonian I, USS Brandywine, the USS Delaware, the U.S. John Adams, the U.S. Frigate Wabash, the S.S. Savannah, the U.S. Colorado, the Niagara Flag Ship, and the San Jacinto at Saint Lawrence, Key West during the Civil War. He was present during the Gold Rush of 1849 in California. During the Civil War he was stationed at the Gulf Blockading Squadron at Key West, Florida.