Dear Mr. Forbis,
Thank you for posting your request on History Hub!
If the county in which he died did not record and issue death certificates, none would exist for him. There may have been a death notice in a local newspaper or the newspaper of his hometown. To search historic American newspapers, visit the Library of Congress’s Chronicling America website.
If he served in the US military, then there maybe a record of his service. We searched the National Park Service’s Civil War Soldiers and Sailors System and located a listing for Forbis, Eli H. assigned to the 32nd Regiment, Illinois Infantry, which may be a match for your ancestor. We searched the National Archives Catalog and located the series titled Carded Records Showing Military Service of Soldiers Who Fought in Volunteer Organizations During the American Civil War in the Records of the Adjutant General's Office, 1762 - 1917 (Record Group 94). Most of the service records in this series have been made available via microfilm and through digitization of the microfilm. Unfortunately, the records for Illinois Volunteers have not been microfilmed or digitized.
We also located the Regimental and Company Books of the 32nd Illinois Infantry Regiment in the record series Regimental and Company Books of Civil War Volunteer Union Organizations, 1861 - 1867 in Record Group 94.
Plus, we located multiple record series relating to Civil War casualties, to include Chronological Index to Casualty Lists, 1861 - 1865, Civil War Regimental Casualty Lists, 1861 - 1865, and Surgeons' Reports on Medical Operations in Various Commands, 1861 - 1865 in Record Group 94.
If he had a surviving widow or dependent that applied for a pension, there may be a listing for him on the General Index to Civil War and Later Pension Files in the Records of the Department of Veterans Affairs (Record Group 15) and a case file relating to him in Case Files of Approved Pension Applications of Widows and Other Dependents of the Army and Navy Who Served Mainly in the Civil War and the War With Spain, 1861 - 1934 or Case Files of Pension Applications Based on Service Completed in the Years 1817 to Approximately 1903.
These records and other Civil War related records are in the custody of the National Archives at Washington, DC - Textual Reference (RDT1). To access these records, please contact RDT1 via email at firstname.lastname@example.org.
We hope this information is helpful. Best of luck with your family research!