This Regiment was organized at Mattoon, Ill, by Colonel James Monroe (then Major of the Seventh Illinois Infantry).  Companies A, C, D, H,  I and K being from Coles county; B from Cumberland, E from Clark, F and G from Clark and Crawford. It was mustered into service at Camp Terry, Mattoon, September 6, 1862, with James Monroe as Colonel, Jonathan Biggs, of Westfield, Clark county, as Lieutenant Colonel, and James A. Connolly, of Charleston, Ill, as Major.

On the 19th of September, 1862, the Regiment was loaded into freight cars at Mattoon, and transported to Louisville, Ky., where it was at once put to work, under General Nelson, to fortify the city against Bragg who was then advancing on it in pursuit of Buell.

October 1, having been assigned to the Thirty-third Brigade (General W. H. Terrill), Fourth Division (General James S. Jackson), in McCook's Corps, the Regiment started on the march under Buell, southward through Kentucky, after Bragg. who had turned back, and up to this time the Regiment never had battalion drill and hardly an attempt at company drill, as all the officers, except the Colonel, were "raw recruits."

October 8, just nineteen days after leaving Mattoon, the Regiment was engaged in the battle of Perryville, where it lost 36 killed and 180 wounded.  Among its wounded were Captain Coblentz, Company E, First Lieutenant S. M. Shepard, Company A. and Adjutant L H. Haslin. Its Brigade Commander, General Terrill, and its Division Commander, General Jackson, were both killed immediately behind and within twenty feet of the line of the Regiment.

October 12, moved through Danville, Ky., to the Kentucky River, thence back through Danville and Lebanon to Mumfordsville, Ky.

In November moved via Glasgow and Bledsoe's Creek to Castilian Springs.

December 26, marched in pursuit of John Morgan, to Glasgow and Bear Wallow.

January 2, 1863, abandoned the chase after Morgan, and under Colonel Hall. One Hundred and Fifth Ohio, commanding Brigade, marched to Cave City, Bowling Green and Nashville, Tenn.,  reaching Murfreesboro. Tenn., in General Gilbert's Corps. January 10.

February and March were spent in brigade and regimental scouting.

Early in March the Regiment was attacked beyond Stone River, while halted on Breed's Hill, with arms stacked and ranks broken, by a large cavalry force, but forming under fire, and repelling the attack, it waded Stone River, carrying off its wounded, and withdrew to Murfreesboro.

March 20, the Brigade, consisting of the One Hundred and Twenty-third Illinois, Eightieth Illinois, One Hundred and Fifth Ohio, One Hundred and First Indiana, with two pieces of Captain Harris' Battery --about 1,500 men in all-- was attacked and surrounded by Morgan's Cavalry, about 5,000 strong, with six pieces of artillery, near Milton, Tenn., about twelve miles out from Murfreesboro. This was shortly after Morgan had captured a Brigade of infantry at Hartsville, Tenn. In the engagement at Milton, Morgan was wounded, his force driven from the field, leaving their dead and wounded and two pieces of artillery. Captain A. C. VanBuskirk, Company H, was killed, and a number wounded.

Major Connolly had the pommel of his addle torn away by a bullet, and dismounting, was In a few minutes knocked down and seriously Injured by a bullet which carried away the collar of his overcoat and blouse. Dr. H. C. Allen, the Regimental Surgeon, had his blouse riddled with bullets while attending to the wounded. Morgan never fought a successful battle after this.

May 6 the Regiment was assigned to Wilder's Brigade, Reynolds' Division, Fourteenth Corps, composed of Seventeenth and Seventy-second Indiana, and Ninety-Eighth and One Hundred and Twenty-third Illinois. They were mounted, and armed with Spencer rifles--seven shooters. Did scouting and patrol duty for a month or so.

June 24 this Brigade led the advance of Rosecrans' army in its movement from Murfreesboro, the Seventeenth Indiana being in advance and the One Hundred and Twenty-third Illinois next. These two Regiments moved out from Murfreesboro long before daylight on the morning of the 24th, in a drenching rain, and by daylight encountered the rebel videttes. From that moment the two Regiments broke into a gallop and kept up the run. The farther they went the larger the rebel force of cavalry kept growing before them, but the rapid pace gave the enemy no time to form, until about 9 o'clock, in the morning by which time the two Regiments had advanced to and seized Hoover's Gap, a plan of great natural strength, but they were confronted here with twenty times their own number of infantry, well supplied with artillery to occupy this Gap, and their supporting forces were at least ten miles in the rear, floundering along through the mud and rain. But the rapidity and audacity of the movement saved them, for the enemy, supposing the force was a large one, checked there advance in column, deployed the force in two lines, brought up there artillery and opened a terrific artillery fire, at the same time sending out reconnoitering parties on the Federal flanks, but as soon as the gap was seized, couriers had been dispatched back to Wilder, informing him of the situation, and before the enemy had satisfied himself of the force in his front, the other Regiments of the Brigade arrived, and with it the battery of Captain Lilly, (Indiana) his guns having been hauled the last mile by men of the Brigade. Lilly's horses having given out with their long run through the muddy roads.

These reinforcements checked the enemy still more, but by 2 P. M. they made a determined attack along the whole line and on both flanks, but the seven shooting Spencer rifles proved effective in repelling it, and before another could be made the head of the Infantry of Rosecrans' army began to arrive, and Hoover's Gap was held without further contest, the enemy withdrawing in the night. The Regiment lost several killed and wounded in this affair.

June 26 to August 16, raiding to the rear of Bragg's army, cutting and tearing up railroads, and burning bridges in his rear; capturing horses and contrabands in the vicinity of Manchester, War Trace, Shelbyville, Columbia, Centerville, Pulaski and Decherd

August 16, moved eastward from Decherd, over Cumberland Mountains and Walden's Ridge, reaching the valley on the east side of the Ridge, at Poe's tavern, about 10 o'clock at night, and there bivouacing until 3 o'clock in the morning, when Major Connolly, of the One Hundred and Twenty-third, was ordered to move down the valley with two companies of his regiment, and, moving cautiously and without noise, to go as far don the valley as he could. This battalion moved on at smart pace and noiselessly over the sandy road, until about 6 o'clock in the morning, when, upon making a turn in the road, the battalion suddenly found itself within 100 yards of the Tennessee River, and looking right up the main street of the city, while the high fortified hill, on the Chattanooga side, with its many guns, frowned immediately over the heads of the men of the battalion, but there was a steamboat lying at the bank on the north side of the river, just where the road they were traveling reached the water, which had just unloaded 60 mules and twelve rebel soldiers, who were bringing the mules out to pasture. In an instant the battalion was flying down the road to that steamboat, the mules and soldiers were captured, and the Spencer rifles began firing into the boat, which dropped its gang plank into the river, and backed out from the bank, drifting down with the current, as the helmsman was compelled to desert his wheel. In the excitement of the attack some of the men rode their horses belly-deep into the river, in their eager desire to capture the boat. The enemy in the city were completely surprised; they didn't know there was a Federal soldier within 100 miles of the city, so the little battalion stood there and fired across into the streets at every rebel uniform that showed itself dodging about the streets, for full ten minutes before a single shot was returned from the other side. Couriers were sent back to notify the Brigade Commander, and, in a very short time, the rest of the Brigade, with Captain Lilly's battery, was on the hills opposite Chattanooga, and Lilly, with his rifled guns, soon found himself able to send his shells entirely over the city and to any part of it. The Regiment remained there with its Brigade, picketing the river for miles above and below Chattanooga, until Sept. 9, when Crittenden's Corps entered Chattanooga.

The Regiment then forded the river above Chattanooga, and led the advance of Crittenden's Corps to Ringgold and Tunnel Hill, Ga., constantly skirmishing during the three days advance.

September 18 and 19, engaged in the battle of Chickamauga, the Regiment taking its place in line with the Infantry of the Fourteenth Corps, to which it belonged

September 20, the Regiment remounted and moved with its Brigade back through Chattanooga, and, crossing the river, moved up to Fryer's Island.

Sergeant Major R. W. Houghton was killed, and Captain W. E. Adams, Company I, was wounded at Chickamauga.

September 24, Major Connolly was detailed to serve as inspector of the Third Division, Fourteenth Corps (General Reynolds) and, on the reorganization of the army, the Divisions of Reynolds and Brennan were consolidated under command of Baird, and Major Connolly, from that time until the close of the war, served as inspector of this consolidated Division, engaging in the siege of Chattanooga, battles of Lookout Mountain, Mission Ridge, Ringgold, Resaca, Atlanta Campaign, Sherman's march to Savannah and through the Carolinas and Virginia to Washington.

October 1 the Regiment started up the river under General Cook to intercept Wheeler in his raid toward Nashville.

October 7 engaged in the battle at Farmington, Tenn., in which Wheeler was severely punished and driven from the State, and where Colonel James Monroe was killed Sergeant Catlin and Corporal Shope were killed also, and many others wounded

Followed Wheeler and drove him across the Tennessee River.

October 19 went into camp at Maysville, Ala., and spent some two months there patroling the surrounding country and collecting horses, thence to Pulaski, Tenn., where two or three weeks were spent in shelter tents, with snow a foot deep and zero weather. Thence to Mooresville, Ala., about the middle of January, 1864, and guarded the Tennessee River, gathering rations and forage in northern Alabama until April; then marched to Columbia, Tenn., remaining there a few weeks; then started to join General Sherman for the Atlanta campaign, passing through Stevenson, Ala., May 6, and camping at foot of Sand Mountain, 7 miles from Bridgeport.

Moved over Sand Mountain through Trenton into Georgia, in Lookout Valley; thence over Lookout Mountain to Chickamauga Creek May 8: thence via Pigeon Gap to Lafayette, across Taylor's Ridge to Villenow, 15 miles from Dalton, and fell in with the army May 11.

May 14 moved towards Rome Ga., with Sherman's Cavalry, but the Cavalry encountered Forrest's Cavalry and Polk's Infantry Corps and retreated, this Regiment being on foot and covering the retreat, wherein their Spencer rifles came into good play.

May 16, at 3 o'clock P. M. started for the front of Sherman's Army, passing on the way the Division of Jeff. C. Davis, en route for Dome, Ga., and at 1 o'clock next morning camped on battle field where Logan's Corps fought for the crossing of the Oostenaula River.

May 19, turned again and moved 18 miles toward Rome. May 18 continued toward Rome, turned toward Kingston, Ga., and at Woodland ran into a rebel force where Adjutant Hamlin was captured.

May 19 the Regiment moved to Rome, the rest of the Brigade going to Kingston, where the Regiment rejoined it the same night.

May 20 the entire Brigade and Garrard's Division of Cavalry behind fortifications at High Tower Bridge.

May 21 Captain O. F. Bane detailed as Adjutant General of Brigade, and Lieutenant L R. Harding relieved as Provost Marshal of Brigade, and detailed as Regimental Adjutant.

May 23 moved 15 miles southwest to VanWert.

May 24 crossed Allatoona Mountains into valley at Dallas and Overtook rear guard of Johnston's army, skirmishing heavily with them,

May 25 moved out of bivouac into line of battle on foot and held line under heavy fire until Logan's Corps came up, when mounting, moved to right flank.

May 27 dismounted behind rail piles on extreme right of army, skirmishing all day; repulsed several charges. By this time the men had acquired much confidence in their Spencer rifles that the single rank formation for line of battle was much better than the double rank used to be with the muzzle loaders.

May 29, changed position during night to extreme left of army.

June 1, Regiment reported to General McPherson, and went into picket southwest of Dallas, on extreme right of army again; constant skirmishing. Covered movement of right wing in changing lines to rear.

June 8, on extreme left of army, at Ackworth. June 9, with Division, reconnoissance to Big Shanty, driving enemy into their earthworks at foot of Kenesaw mountain. Four men of Regiment wounded on skirmish line. June 10, moved four miles to left of Big Shanty, holding left of army; fortified along Noonday Creek.

June 19, moved with the Brigade out of fortifications, and drove the enemy beyond the creek into their fortifications. On 20th, another similar advance, with heavy skirmishing, resulting before.

June 22, made a forty-mile scout eastward to Canton and back, halting at noon on Governor Joe Brown's farm. June 23, Regiment moved with Garrard's Division of Cavalry across Noonday Creek. Daily skirmishing until July 2d, when the Regiment covered the withdrawal of McPherson's Corps again, preparatory to a change of front.

July 3, followed the retiring enemy through Marietta, Ga.

July 4, 1864, skirmishing nearly all day with the enemy, between Marietta and the Chattahoochie, with the Chicago Board of Trade Battery well up to the skirmish line all the time.

July 5, moved toward Roawell, Ga. July 9, waded the Chattahoochie River at Roswell, under fire of enemy from opposite bank, and lay all day on south bank, after driving the enemy away, as cover for the crossing of our troops, wading back at night to hones and bed. July 15, Lieutenant Colonel Biggs led the Regiment, together with the Seventy-second Indiana and Seventh Pennsylvania Cavalry, to Cress Keys, within thirteen miles of Atlanta. July 13, destroyed railroad between Decatur and Stone Mountain Station, and on 19th captured Stone Mountain Station. On 20th moved to Decatur. 22d and 23d of July, on a raid to Oxford and Covington, Ga.

On the night of July 27 Garrard's Division of Cavalry, with which the Regiment was serving, was completely surrounded by a large force of the enemy, and the Regiment was dismounted, and forming as infantry, led the advance in cutting through the lines of the enemy on the Atlanta road, on the morning of July 28. Captain Hart, Company D, was wounded here.

August 1, the Regiment and the rest of the Brigade returned to Atlanta front, and leaving horses at Peach Tree Creek, in charge of the "No. 4" men, moved into the line of works on extreme left, which the Twenty-third Corps had vacated daring the night, and continued to hold them until the 13th, when moved to Decatur. 17th in camp on Buck Head road. 19th and 20th, at Decatur, patroling, skirmishing and foraging in rear of Atlanta until night of 20th, when the Regiment traveled and picketed all night for the left wing of the army as it withdrew to the Chattahoochie River.

August 29, moved to right of the army with the Brigade, and on 30th covered movement of army trains, and reached Montgomery railroad. On 30th moved to right near to Macon railroad, which Scotfield was destroying at Rough-and-Ready.

September 2 reconnoitred in rear of Atlanta, which was taken possession of by Slocum, and Atlanta campaign ended, the Regiment having marched as cavalry and fought as infantry all through it.

October 1st at Cross Keys. October 3d, crossed the Chattahoochie on pontoons, going northward in pursuit of Hood. October 5th, followed Hood to Lost Mountain, the Fourth Corps being to the right and the Fourteenth Corps to the left, October 7th, fought the enemy at New Hope Church, we occupying their old works and they occupying ours. October 11th, reached Rome, and on 12th engaged enemy, driving him three or four miles from Rome in direction of Summerville. 13th, moved east on old Atlanta road and scattered enemy's cavalry over the country. 14th, moved on Kingston road. October 20th, came up with Hood at Little River, and spent day in heavy skirmishing, being then in Alabama. 21st, struck enemy again at Blue Fond

October 23d, moved over Lookout Mountain into Wills Valley, Hood's army having left Gadsden, Ala., for the Tennessee River. October 28th, struck the enemy at Terrapin Creek. General J. H. Wilson assumed command of the Division to which the Regiment was attached, and which was commanded by General Garrard during all the Atlanta campaign and up to this date.

October 30th, reached Cave Springs, and next day reached Rome. November 1st, turned over all serviceable horses and mules to General Kilpatrick, and went to Louisville, Ky., to remount for the "Wilson Raid" of the next spring.

December 28th, 1864, left Louisville, Ky., remounted and equipped.

January 1st, 1865, camped at Elizabethtown, Ky., with snow a foot deep and weather very cold. January 9th, 10th and 11th, at Nashville, Tenn. Moved thence via Columbia and Mt. Pleasant to Gravelly Springs, Ala., near Eastport.

March 23d, 1865, started from there with First, Second and Fourth Divisions of cavalry, 12,000 men, under General Wilson, for Selma, Ala. 23d March, reached Frankfort, and 24th crossed Bear Creek. March 26th, reached Blackwater River, and on 29th reached Black Warrior, whose waters flow directly to the Gulf. March 30th, marched through Eliton and camped 11 miles below, having marched 30 miles this day. March 31st, moved down the railroad toward Selma, destroying bridges, trestlework, depots and Confederate machine shops at Limestone Station. Montevallo was captured after sharp fighting, and burned..

April 1st, rebels sent reinforcements up from Selma and made a determined stand at Ebenezer Church, but they were forced back with but little fighting.. April 2d, marched 21 miles, appearing before Selma's fortifications at two o'clock in the afternoon. Immediately the horses were sent to the rear, lines formed, and an assault commenced on the works by the mounted Infantry Brigade with their Spencer rifles.

The assaulting column consisted of but little over 1,000 men, in singie line, and with no reserve line. This column was composed of the Ninety-eighth and One Hundred and Twenty-third Illinois and Seventeenth and Seventy-second Indiana, and when the command to charge was given they rushed forward under a deadly fire without check or waver until they climbed the fortifications and opened their deadly Spencer fire on the flying defenders of Selma. In this assault, First Lieutenant 0. J. McManus, Sergeants J. S. Mullen and Henry E. Cross, Corporal McMurry and privates Daniel Cook, John Bowman, Marion White and Henry Woodruff were killed, and 50 wounded, including Lieutenant Colonel Biggs, Adjutant L. B. Bane, Captains W. E. Adams and Owen Wiley, Lieutenants Alex. McNutt and J. R. Harding.

Forrest was defending the place with 8,000 men. He escaped, leaving 2,000 prisoners in our hands.

April 8th, marched for Montgomery, 45 miles away, wading swamps and creeks and pontooning Black Swan River, reaching the original capital of the Confederacy on April 13th, and there learning for the first time that Lee had surrendered to Grant In Virginia.

April 16th, reached Columbus, Ga., and on the 20th entered Macon, Ga., without opposition, at the end of a 43 miles march. May 23d, started for Chattanooga; from thence marched to Nashville and camped across the river at Edgefield, where the Regiment was mustered for discharge by Captain L. M. Hosea a June 27th, the recruits being transferred to the Sixty-first Illinois. Discharged at Springfield, Ill., July 11th, 1865. At the time of the death of Colonel Monroe, at Farmington, Tenn., in October, 1863, the Regiment was reduced below the minimum, and was never after filled up, so that the Lieutenant Colonel and Major came home with the same rank they went out with, except that the Lieutenant Colonel was brevetted Brigadier General, and the Major was brevetted Lieutenant Colonel by the President.

SPECIAL ORDERS }
NO. 5.                      } EXTRACT                                                                          NASHVILLE, TENN., June 28, 1865,

XXVII. Those men of the One Hundred and Twenty-third Illinois Volunteers who are ineligible to be mustered out with that command, now at Edgefield, Tenn., will proceed, without delay, to Franklin, Tenn., under charge of Lieutenant L. Grundy, Sixty-first Illinois. On arrival at Franklin, these men will be transferred to and permanently consolidated with the Sixty-first Illinois Volunteer Infantry. Brevet Major A. L. Hough, Chief Commissary of Musters, M. D. T., is hereby charged with the execution of this order. The transfer to be made under provisions of Circular No. 64, series 1864, War Department
    By command of Major General Thomas.