The regiment left Ohio for Baltimore, Maryland, May 17 and was assigned to Tyler's Command, VIII Corps.
Duty in the defenses of Baltimore and at Fort Delaware guarding Confederate prisoners until September.
Shipped to the Eastern Theater, they were designed to be placed in "safe" rear areas to protect railroads and supply points, thereby freeing regular troops for Lt. Gen. Ulysses S. Grant’s push on the Confederate capital of Richmond, Virginia.
Ohio Guard units met the battle-tested foe head on and helped blunt the Confederate offensive thereby saving Washington, D.C. from capture.
Ohio National Guard units participated in the battles of Monacacy, Fort Stevens, Harpers Ferry, and in the siege of Petersburg.