Dear Mr. Griffiths,
Thank you for posting your request on History Hub!
We searched the National Archives Catalog and located a series titled Lists, 1862 - 1865 in the Records of U.S. Army Continental Commands (Record Group 393) that includes lists of prisoners at Fort Monroe and of persons taking the oath of allegiance to the United States. We also located two series titled Register of Rebel Deserters and Refugees at Fort Monroe, Virginia, 9/1863 - 2/1865 and Lists of Military and Civilian Personnel Signing Paroles with Honor, 1863 - 1864 in Record Group 393 that may include Edgar Simpson. For access to and/or copies of these records, please contact the National Archives at Washington, DC - Textual Reference (RDT1) via email at firstname.lastname@example.org.
We suggest that you review NARA’s Civil War Military Records; and the Library of Congress’ Civil War Conscription Laws websites for research information and resources. You may also wish to review Desertion in the Confederate Army: A Disease that Crippled Dixie; Desertion, Cowardice and Punishment; and Desertion (Confederate) during the Civil War for additional information.
We hope this is helpful. Best of luck with your research!