The 5th Ohio Infantry Regiment was an infantry regiment from southwestern Ohio that served in the Union Army during the American Civil War, serving in both the Eastern and Western Theaters in a series of campaigns and battles. It was noted for its holding the high ground at the center of the line at Antietam as part of Tyndale's 1st Brigade, Greene's 2nd Division of Mansfield's XII Corps. Organization and service The 5th Ohio Infantry Regiment was organized at Camp Harrison near Cincinnati on 20 April 1861, for three months service. The men were mustered into service on 8 May. The regiment moved to Camp Dennison on 23 May, and was on duty there until 20 June. After its initial term of enlistment expired, the regiment was reorganized on 20 June 1861, for three years, under Colonel Samuel H. Dunning. The remaining three-months men who did not re-enlist in the new regiment were mustered out on 24 July. The regiment served in western Virginia for most of the balance of the year. In 1862, the regiment was sent into Virginia's Shenandoah Valley, where it suffered significant casualties during First Battle of Kernstown in March. At the subsequent Battle of Port Republic on 9 June, the Buckeyes lost 244 killed, wounded and prisoners. Its ranks much depleted from the Valley Campaign, the regiment served in the defenses of Washington, D.C. under John Pope and participated in the Northern Virginia Campaign. The 5th Ohio Infantry was heavily involved in the fighting at the Battle of Antietam on 17 September 1862. It was part of Major General Joseph Mansfield's XII Corps and Lt. Col. Hector Tyndale's Brigade, along with the 7th Ohio Infantry, 66th Ohio Infantry, and 28th Pennsylvania Infantry Regiments. Entering the battle in support of Joseph Hooker's I Corps, Tyndale's brigade inflicted heavy casualties on Alfred H. Colquitt's brigade and helped drive the Confederates out of the Cornfield. Pushing the Confederates south to the Dunker Church, Tyndale's men held the area until the afternoon when lack of support, heavy losses and low ammunition compelled them to retreat. In 1863, the partially replenished 5th Ohio Infantry fought in the Army of the Potomac at Chancellorsville and then served in the Gettysburg Campaign. Transferred later in the summer to the Western Theater and becoming part of the XX Corps under Joseph Hooker, the regiment participated in the Battle of Lookout Mountain near Chattanooga,