1st Ohio Infantry

1st Regiment, Ohio Volunteer Infantry
1st Ohio Infantry in action at Vienna, Virginia June 17, 1861
Active	1861–64
Country	United States
Allegiance	Union
Branch	Infantry
Type	Regiment
Size	950 soldiers at outset of the war
Engagements	Shiloh, Stones River, Chickamauga, Missionary Ridge, Atlanta Campaign
Commanders
Notable commanders	Alexander M. McCook

The 1st Regiment, Ohio Volunteer Infantry (or 1st OVI) was an infantry regiment in the Union Army during the American Civil War. It served in the Western Theater in a number of campaigns and battles.

With the outbreak of the Civil War in the spring of 1861, President Abraham Lincoln called for 75,000 volunteers from nearly every state. In April, recruiters quickly filled the quota for a number of regiments in the state of Ohio, with several regiments enlisting for 3-months, including a command designated as the 1st Ohio. Mustering in April 17, 1861, under Colonel Alexander M. McCook, it travelled by train to Washington, D.C. for garrison duty in the capital's fortifications and defenses until July. The regiment was placed in Schenck's Brigade, Tyler's Division, Irvin McDowell's Army of Northeastern Virginia. It first saw action at Vienna, Virginia, on June 17 and again on July 9 before occupying Fairfax Court House. It fought at the First Battle of Bull Run and helped cover the army's bitter retreat to Washington. The regiment soon returned to Ohio and mustered out August 2.

After the term of service was over in August, a number of the men re-enlisted for 3-years in the reconstituted 1st OVI, under the command of Col. Benjamin F. Smith. The regiment was organized at Camp Corwin in Dayton between August 5 and October 30, receiving muskets, uniforms, and accoutrements. On the last day of August, the regiment entrained for Cincinnati for additional training and guard duty. The 1st OVI left Ohio in November 1861 for Louisville, Kentucky. From there, they were posted in a number of Kentucky towns through February 1862, striving to keep the border state in the Union.