The Hiram W. Coppernall collection pertains to his service in the 24th New York Cavalry Regiment, Company H, during the Civil War. Throughout 1864, he kept a diary (120 pages), which concerns his military training, his unit's marches through Virginia, his participation in the Battle of Petersburg, and his affliction with severe sunstroke. He began writing shortly after his enlistment, and a woman named "Eliza" contributed some early entries in which she apologized for intruding and encouraged Coppernall to remember and write to her. After training and performing police duty in Washington, D.C., the regiment left for Virginia in late April. On May 7, they constructed a breastwork, and on May 18-19 they traveled to Spotsylvania Court House. Coppernall occasionally reported on military engagements that often ended in Union defeats. On June 18, he participated in an assault on Petersburg, Virginia, and on July 30 he mentioned a tunnel explosion and the resulting Battle of the Crater. He wrote less frequently after August 6, when he suffered from severe sunstroke, and he spent much of the rest of the year recuperating and on furlough in New York. He rejoined his regiment in December. In addition to Coppernall's diary entries, the volume has a list of men in his regiment and financial accounts, which include a list of the clothing he received from the United States government for his military service. The diary is accompanied by a carte-de-visite photograph of Coppernall and a framed photograph of two Union cavalry officers, with the message "Same here" (1864).