The 23rd Ohio Infantry Regiment was an infantry regiment in the Union Army during much of the American Civil War. It served in the Eastern Theater in a variety of campaigns and battles, and is remembered with a stone memorial on the Antietam National Battlefield not far from Burnside's Bridge.

The regiment later became noted for its many up-and-coming politicians. Future presidents Rutherford B. Hayes and William McKinley served in this unit, as did future U.S. senator and associate justice of the United States Supreme Court Stanley Matthews and Robert P. Kennedy, a future U.S. Congressman. Other notable officers included James M. Comly and Eliakim P. Scammon, both of whom became influential nationally after the war. Harrison Gray Otis, the famed owner and publisher of the Los Angeles Times, also fought with the 23rd Ohio during the war. All told, before the regiment was mustered out at war's end, it had seen five generals serve in it.

Service Under the first call of President Abraham Lincoln, Ohio sent to the field 22 regiments of infantry, each having been enlisted for three months only. While these organizations organized for three months' service, Lincoln issued a call for a further 300,000 men for three years enlistment. Nearly all the companies which became the 23rd Ohio were then waiting to muster in for three months in different parts of Ohio. These·companies were the Bellefontaine Rifles from Logan County, the Cleveland Rifle Grenadiers with men from both Cleveland in Cuyahoga County and Wellington in Lorain County, the Ellsworth Guards from Ashland County, the Elyria Rifle Guards from Lorain County, the Galion Guards of Crawford County, Giddings's Zouaves from Ashtabula County, the Ohio Union Savers from Lake County, the Poland Guards from eastern Mahoning County, Ohio, the Welker Guards from Holmes and Ashland Counties, and the Zouave Light Guards from Cuyahoga County. These units were ordered to Camp Chase, near Columbus, and were re-enlisted for three years and assigned to the regiment. This made the 23rd Regiment the first three-year Ohio Volunteer Infantry regiment organized. Governor William Dennison soon gave commissions to several of the officers of the volunteer companies. The regiment mustered into duty on Tuesday, June 11, 1861, by Capt. Howard Stansberry, USA, as a three-year regiment.

Its 950 enlistees were originally led by Col. William Rosecrans. The other initial field officers were Lieutenant-Colonel Stanley Mathews and Major Rutherford B. Hayes, however, changes in the field/staff came quickly. That Friday, June 14, Rosecrans was promoted to Brigadier-General in the regular army. Wisely opting not to be promoted above their experience and ability, Matthews and Hayes asked for another regular officer to take command. In late June, 1837 West Point graduate and Mexican-American War veteran, Col. Eliakim P. Scammon succeeded Rosecrans in command. As well as the colonel and lieutenant-colonel, the quartermaster and adjutant were also promoted and transferred. They were replaced by promotions from the regiment, except for Major James M. Comly, who was transferred from the 63d Ohio. Hayes was promoted to lieutenant-colonel.

The 18-year-old Poland, Ohio resident, McKinley quickly adapted to army life and also wrote a series of letters to his hometown newspaper extolling the army and the Union cause. While at Camp Chase, their first shipment of official clothing contained only undershirts and drawers followed later by full uniforms. These delays in issuance of uniforms and weapons again brought the men into conflict with their officers, but recently appointed Major Hayes convinced them to accept what the government had issued them; his style in dealing with the men impressed McKinley, beginning an association and friendship that would last until Hayes's death in 1893. A few weeks later, though, the men were further disappointed when their first issue of arms were flintlock muskets on July 23. After much effort by the staff, the men accepted the arms.

1861: Initial deployment After training and drilling following their induction, on Thursday, July 25, 1861, the regiment was ordered to Clarksburg, for western Virginia, where it arrived by train on Saturday. It served for several months in this area of current West Virginia, helping to restore that portion of Virginia to the Union. The 23rd Ohio was attached to Jacob D. Cox's Kanawha Brigade and served throughout much of the war in what became the IX Corps.

Ordered to garrison the town of Weston, roughly away, the 23rd Ohio marched for two days through heavy rain followed by an intense heat. Scammon continually chided his raw recruits for their slow pace and for discarding equipment en route. Shortly after arrival, Scammon was ordered to divide his command into two battalions of five companies to better counter the partisan threat. One battalion under Lt. Col. Mathews as a movable force, dedicated to counterinsurgency that was sent a further south to the vicinity of Bulltown and Sutton, under Matthews. The remaining battalion of five companies stayed at Weston with Scammon sending out occasional foraging and scouting expeditions against guerrillas and other disaffected inhabitants. This division of force elicited no response from the Rebel military who had suffered crushing defeats in the in western Virginia and opted not to devote many resources to what they deemed an area of relatively limited value.

In this area, the 23rd Ohio operated against numerous secessionist guerrillas there, performing hard duty, marching and countermarching over the rugged mountainous terrain drenched by almost continuous rain. Despite not being in the main theater of the war, life for the men in the regiment was often vicious and dangerous. It was an unpleasant constabulary duty that lacked the military glory many had sought to experience. They found the locals divided in their loyalties, with many serving in both Confederate and U. S. armies The 23rd Ohio was soon in a constant mode of incessant patrols chasing small bands of secessionist guerilla whose actions kept U.S. forces tied down and anxious.

Hope for real action rose in mid-August when Scammon was ordered south to join Rosecrans force assembling to counter a Rebel offensive in the Kanawha Valley. This valley and county was the center of the slavery in what would soon be West Virginia. The salt industry had brought slavery into the mountains and made slave-owners extremely wealthy and politically powerful. The wealth of the slave owners and their dominance of the economy gave them a sense of entitlement when it came to local politics and laws requiring bonds to be posted before running for office as a nominal anti-corruption matter negated the gains of universal white suffrage in 1851. Due to the vocal unionist majority in the region, the local slave-owning elite had raised militia companies to assert political control over the county and when few volunteers responded to their calls for resistance to Federal forces entering the region, they appealed to Richmond to maintain their political control. This Rebel force, under former Virginia governor Henry A. Wise, entered the valley and immediately began asserting arresting Unionists and destroying their property. After winning the Battle of Scary Creek, Wise found himself facing greater enemy numbers and suffered a strategic defeat as he withdrew southeast to Greenbrier County.

In September, the Confederacy again tried to wrest control of the valley from the United States. In this part of then Virginia, the Carnifex Ferry was a key part of the major roads in the area. This ferry operated southwest of Summersville. It was, for many miles, practically the only crossing along the rugged Gauley River. In 1861, it was 370 feet in width and crossed by means of two flatboats. The road from the crossing wound along the base of the cliffs on the north side. On August 12, 1861, Brig. Gen. John Buchanan Floyd, former Secretary of War and like Wise – a former governor of Virginia, had entered Lewisburg with troops raised largely in southwestern Virginia. Advised to hold the ferry, but warned to stay on the south bank, he crossed the Gauley on Wednesday evening, August 22 and on August 26, attacked and routed Col. Erastus B. Tyler's 7th Ohio Infantry encamped at Kessler's Cross Lanes. After this battle, he returned to fortify the ferry from where he planned to move against Rosecrans by occupying Summersville, and sent Col. John McCausland, with the 36th Virginia Infantry (Second Kanawha), occupied the town of Summersville.

Upon entering the valley after Wise's withdrawal, the men of the 23rd Ohio and their comrades had been warmly welcomed into the area by many local citizens reflecting the loyalty division. Sgt. McKinley's passage through the town of Sutton exposed him to the devastation neighbor had wrought upon neighbor with few civilians about many dwellings destroyed and those that were not occupied by Federal troops. On Sunday, September 1, Matthews and his five companies reunited with the regiment at Bulltown, and the 23rd Ohio left for Sutton to join Rosecrans's Army of West Virginia. The regiment was now part of an army of 8,000—eight infantry regiments, three mounted batteries, and three cavalry companies—under Rosecrans' command, with the 23rd serving as the commander's bodyguard.

Scammon took command of the 3rd Brigade composed of the 23rd and 30th Ohio regiments. Due to Matthews' absence, Hayes took command of the regiment. Leaving a garrison of around 3,000 men at Sutton, the following Saturday, September 7, the army moved south towards Summersville. Rosecrans' expedition moved out of Sutton with a squadron of cavalry in front followed by pioneers. Next in the van was Benham's 1st Brigade followed by McCook's 2nd Brigade. The 3rd Brigade was the last combat unit in the column. Per Rosecrans' direction, Scammon had detailed six companies of the 30th Ohio to guard the a wagon train that trailed out for five miles. After a hard slog, Rosecrans had his men stop at Birch River Sunday evening where he received intelligence that Floyd was at the ferry.Late Monday morning, September 9, the march resumed and that night halted from Summersville, on Muddlety Creek, on the site of a former Confederate outpost.

As the 23rd Ohio and the Army of West Virginia approached, McCausland, recognizing he was isolated and outnumbered, had withdrawn to rejoin Floyd at the ferry on Sunday. Floyd now had about 2000 men in fortifications as the U.S. force of 5,000 approached. Scouts reported back to Rosecrans that the Rebels were still at the ferry.

At 4:00 am, on Tuesday, Rosecrans moved forward. The advance guard reached Summersville about 8:45 am. Near McKee's Creek Crossing was a road that led to Hughes Ferry on Gauley River, at the mouth of Salmon Run. McCook, with a cavalry escort, rode down to the river and was fired upon by a Confederate detachment. Four companies of the 10th Ohio then came to the rescue, and the ferry boat was secured and the march resumed. The road then led southwest to Kessler's Cross Lanes where Rosecrans paused from the crossroad for a short rest of short duration. He then sent Benham's 1st Brigade down the road leading from Cross Lanes to the ferry in line of battle, cautioning him not to bring on an engagement as while Floyd's general location was known, the disposition of his troops was not.