The captains of the several companies were: A. Charles H. Weygant; B. Henry S. Murray: C. Wm. Silliman; D. James W. Benedict: E. Wm. A. McBirney; F. Ira S. Bush; G. Isaac Nicoll; H. David Crist; I. Leander Clark; K. Wm. A. Jackson.

Delay in obtaining guns postponed the mustering in of the regiment until September 5th, and the next day it broke camp at Goshen and started for Washington. Meanwhile it had been presented by Charles H. Winfield, in behalf of the ladies of Orange, with a stand of colors. Its fine appearance in New York inspired a paragraph of praise from the Tribune, which said that the most influential families of Orange County were represented in its ranks, and that it contained "the very cream of the regimental district."

Three days afterward they were in Washington, and the first night there slept on the ground and stone block in front of the Capitol. The next day they marched to Camp Chase on Arlington Heights, and two or three days later moved to a spot which they christened Camp Ellis. Here they were attached to Platt's brigade of Whipple's division of Heintzleman's corps. The other regiments in the brigade were the 122nd Pa. (a nine months regiment), the 86th N. Y., and the 1st Ohio battery. The 124th and 86th regiments remained together during the war. The latter and the Ohio battery were already veterans.

The 124th broke camp again September 25th, went to Miners' Hill, and here the men became experienced in picket duties. Tents were struck October 16th, and the next day they started in a drizzling rain with their division to join the main army on the Maryland side of the Potomac in the vicinity of Harper's Ferry. A freight train carried them in great discomfort from Washington to Knoxville, eight miles from Harper's Ferry, and they became a part of the Army of the Potomac. October 25th they again received marching orders, and were in motion from supper time till midnight, when they bivouacked near Berlin, where a pontoon bridge was being laid. Across this they went with the entire army of 100,000 men, and were afterward halted in a muddy cornfield near Lovettsville, where they had to stay all night in rain, a cold wind and mud, and had their first realization of the sufferings of army life. The next morning thirty of the men were unfit for duty. Short marches were continued, with stops of two or three days, they being in the advance with the rest of Whipple division a part of the time, and then they looked from a peak of the Blue Ridge upon some white tents of the enemy. The object of the movement had been to cut off a force of his infantry, but it was too late and the division was ordered to retrace its steps.

At Orleans they learned that McClellan had been succeeded by Burnside as commander of the Army of the Potomac. November 11th they marched to Waterloo, and here some of the men of Co. B, commanded by Lieutenant W. E. Weygant, were part of a detail which had a fight with the enemy's pickets and captured two prisoners. November 16th they marched to Warrenton and here became a part of General Hooker's grand division. There were now daily marches, some of the time through heavy rains and in deep mud. November 23rd, four miles from Fredericksburg, they went into camp for the first time since leaving Miner's Hill. The army waited in that vicinity for the pontoon trains, which did not arrive until December 10. Then, in pushing a pontoon bridge across the Rappahannock, many of the builders were killed by Mississippi sharpshooters. To stop this 120 cannon were placed on Stafford Heights overlooking Fredericksburg, and began firing shells into the city and among the sharpshooters. When the firing ceased two bridges spanned the river, and Union troops hurried across and soon drove the enemy out of Fredericksburg. But the great battle was yet to come, when the Confederates forced Burnside's army to withdraw to Falmouth after losing 13,000 men. Platt's brigade formed the extreme right of the line, and the 124th was one of the last regiments to recross the bridges. The next morning about half of the men answered to the surgeon's call, and nearly a hundred were placed on the sick list. General Platt resigned about Christmas time, and there was a period of drilling and picket duty by brigades. January 5th the corps was reviewed by General Burnside. January 10th new Enfield rifles came and were substituted for the old Belgians. Then, after three or four orders to march had been countermanded, a start was made through pelting rain and sleet and deepening mud. The rain and sleet froze as it fell, and the men were chilled, and experienced two nights of great suffering. General Burnside abandoned the attempt to advance. On January 26th General Hooker superseded him. The division moved a little way, and cut down trees and constructed log cabins. During February the weather was severe, but the log cabins, which had fire places, though smoky at times, made them tolerably comfortable. February 25th the 124th drove off a body of Confederate cavalry which made a dash on their picket line. There was a monotonous interval, enlivened April 7th by a grand review before President Lincoln and Generals Hooker and Sickles. The division and brigade were then attached to General Sickles's corps. Orders to march came April 28th, and the entire army was soon in motion, and the next day halted in sight of the enemy's pickets across the Rappahannock. The 124th crossed the river on a pontoon bridge with an army of 65,000 men, thirteen miles from Fredericksburg. Then came the disastrous battle of Chancellorsville, during which the 124th got into the thickest of the fight, had a fierce encounter with Iverson's brigade, and "not a man faltered," although raked by a deadly fire in which many men and a number of officers fell. Once they made a charge and retook works from which one of our batteries had been driven. The battle ended with the day, and Hooker was whipped. The Third corps lost in killed and wounded 4,000 men. It captured seven battle flags and over 1,000 prisoners. The losses of the 124th were fifty-five killed, 150 wounded and six missing. Colonel Ellis, in his official report said: "Our men fought like tigers, cheering loudly, but falling fast, the officers without exception standing up to their duty and encouraging their commands."

After Chancellorsville the 122nd Pa., having completed its nine months of service, returned home, and the brigade collapsed to between 500 and 600 men of the 86th and 124th. Colonel Ellis was now in command of the brigade, and it was selected as one of three brigades of picked regiments to accompany a large body of cavalry on a secret expedition. They Started May 6th through a thunderstorm to Beverly's Ford, where they crossed the Rappahannock. There had been a clash of cavalry, and Colonel Ellis's regiments were the first in the field. Batteries on both sides opened fire, and there were charges and counter charges, in which bullets flew thick. A body of rebels got in the rear of the 124th, but they were repulsed after a hot contest in which Co.'s A, F and D lost two killed and twenty wounded. The troops were ordered to recross the river.

The 124th did such splendid service at Chancellorsville that it was transferred to the roll of "first class, tried and to be trusted, veteran battalions," although only six weeks before it had been classed among the "untried recruits." June 9th it was part of an expedition of these veteran regiments which recrossed the Rappahannock, did some more fighting, under General Buford, and captured some of the enemy's pickets. General Pleasanton accompanied General Buford and ordered an advance in force, but he found the enemy reinforced and the troops were withdrawn after a loss of about 800 on each side. The 124th and 86th were commended as "reliable regiments" in the day's doings.

About this time the old Whipple division ceased to exist in consequence of the losses at Chancellorsville and mustering-out of several regiments. Berdan's sharpshooters and the 124th and 86th were assigned to General J. H. H. Ward's brigade of General D. B. Birney's division.

On June 14th they started on one of their longest and severest marches northward, and on June 25th crossed the Potomac at Edward's Ferry near Ball's Bluff. Just before it was ordered Milner Brown was assigned to the command of the regiment. They proceeded through Fredericksburg to Emmetsburg, and here on June 30th the 124th had but 264 rifles in line, so great had been the losses in battle and from disease. They were informed that General Hooker had been succeeded by General Meade. The Confederates had invaded Pennsylvania and a great battle was anticipated. A forced march was made to Gettysburg through such intense heat that many were prostrated, and when the regiment reached the high ground south of Gettysburg not more than 100 men and five or six officers appeared in the regimental line, but the next morning it was 240 strong. It was placed in the right center of the brigade, and in that decisive battle of the war distinguished itself by its steadiness and daring. For forty minutes Ward's and De Trobriand's brigades of about 3,000 men held their ground against Longstreet's entire corps. By a mere chance the whole regiment escaped capture. General Ward harangued its men on the battlefield, and said the heroic resistance they had made "was beyond anything he had ever dared to hope for." Its active part in the great three days' battle was finished on the second day, as it was not called upon to participate in the fighting of the third day, which brought defeat to Lee's army. The 124th had lost thirty-three killed, including Colonel Ellis, Major James Cromwell and Captain Isaac Nicoll, and fifty-nine wounded, including Lieutenant Colonel Cummins. A number of the severely wounded remained in the hands of the enemy several days. The regiment was now reduced to 150 men with muskets and nine commissioned officers. Some had been sent to the corps hospital. They were now temporarily commanded by Captain Charles A. Weygant of Co. A.