The companies for the 145th regiment were recruited as follows:

• Company A - Erie County
• Company B - Erie County
• Company C - Erie County
• Company D - Erie County
• Company D - Erie County
• Company E - Warren County
• Company G - Mercer County
• Company H - Crawford
• Company I - Erie County
• Company K - Erie County

They rendezvoused at the camp near the city of Erie, which had been previously occupied by the Eighty-third, and the One Hundred and Eleventh regiments, where, on the 5th of September, 1862, a regimental organization was effected, with the following field officers:

• Hiram L. Brown, of Erie, Colonel
• David B. M'Creary, of Erie, Lieutenant Colonel
• John WV. Patton, of Crawford county, Major

Colonel Brown had served in the Wayne Guards, a militia company of considerable distinction, previous to the opening of the rebellion, as Captain in the three months' Erie Regiment, and as Captain in the Eighty-third, in which he had received a severe wound, at the battle of Gaines' Mill, and from the effect of which he had not entirely recovered when selected to lead this regiment. Lieutenant Colonel M'Creary had also served in the Wayne Guards, and as Lieutenant in the Erie Regiment.

At the time of the organization of the One Hundred and Forty-fifth, there was urgent need of troops. The army of the Potomac was returning from the fruitless campaign upon the Peninsula, and the Army of Northern Virginia, under Pope, was retiring, broken and dispirited, fronm the fated fields of Bull Run. It was, accordingly, ordered to the front, without arms, and with scarcely any knowledge of military duty. It left Erie on the 11th of September, and proceeded by rail via Harrisburg to Chambersburg, arriving in thirty-six hours within sound of the enemy's cannon, Lee having already crossed the Potomac, and penetrated the South Mountain. Halting for two days at Camp 1'Clure, the men were supplied with arms, the old Harper's Ferry musket, and moved under orders from General John P. Reynolds, in command in Pennsylvania, in the direction of Hagerstown.

Battle of Antietam

With but a partial outfit, and men and many officers fresh from civil life, the command experienced much suffering from exposure and inadequate supplies. At daylight on the morning of the 17th, the regiment was under arms, the heavy booming of cannon on the field of Antietam, ten miles away, being distinctly heard. That, sound awakened intense excitement in every breast, and all were impatient to march to the theatre of conflict. This desire was gratified. Though isolated from the grand army, and liable to fall victims to the enemy's cavalry, which was manifesting the greatest activity, Colonel Brown led his command forward, and at a little after noon, arrived upon the extreme right of the Union line, at this time desperately engaged with the Corps of Stonewall Jackson, the hostile shot and shell failing thick on every hand. It was immedliately moved into position, filling a gap which then existed between the Union right and the Potomac, holding the tow-path and the road which runs along under the high bluff skirting the river, thus preventing the enemy from flanking the Union forces in that direction. This position was held, and picket duty performed in face of the enemy, until the morning of the 19th. It was then discovered that the enemy had escaped, and with other troops the regiment was sent upon the field to bury the dead, and care for the wounded. For four days they had lain as they fell, and the stench that filled the air was exeeedingly offensive. The unusual privation and exposure of the men during the few previous days after leaving camp, and the severe duty to which they were su-bjected on this polluted field, resulted in wide-spread sickness. Within a month from the time they had been ordered to the front, between two and three hundred were disqualified for duty. Many died, or were permanently disabled, and were discharged.

Soon after the battle, the regiment went into camp on Bolivar Heights, just above Harper's Ferry, where it was temporarily attached to the Irish Brigade but was finally assigned to the First Brigade, First Division, of the Second Corps, in which it was engaged in picket and guard duty, and in severe drill; the troops with which it was associated having had the experience of a year's discipline and campaigning.

Battle of Fredericksburg

Towards the close of October, the regiment moved with the army down the London Valley to Warrenton, where it made a brief halt and then proceeded towards Falmouth, Burnside being in command of the army, and making every preparation to meet the enemy. The morning of the 11th of Decenmber broke clear and crisp along the Rappahannock, and early the whole army was astir, the battle of Fredericksburg impending. The One Hundred and Forty-fifth crossed on the upper pontoon bridge, on the afternoon of the 12th, and formed in line upon a street running parallel with the river, where it remained during the succeeding night.

On the morning of the 13th, it moved back from the river, two or three streets, its right resting near the Court House, where it came under a heavy artillery fire, and an incessant fusilade from sharp-shooters concealed from view. About noon, the First Division marched by the flank up the streets and out upon the plain, between the town and the battery-crowned hills that encircled it beyond. The One Hundred and Forty-fifth moved forward with the steadiness of veterans, over the deep ditch and snmooth plain, towards the fatal stone-wall at the foot of Marye's Heights, though its ranks were shattered and torn by the fire from concealed infantry, and the batteries which confronted and enfiladed it, until it reached the front line formed by the Union forces. Here it remained until after night-fall, and until the fighting ceased, when the division was relieved, and returned to town.

"Of the five thousand men," says Swinton, "Hancock led into action, more than two thousand fell in that charge; and it was found that the bravest of these had thrown uip their hands and lay dead within five and twenty paces of the stone-wall."

On the night of the 15th the army recrossed the river, and on the following morning the fragment remaining of the One Hundred and Forty-fifth, took possession of its old quarters upon Stafford Heights. On the morning previous to the battle, flive hundred and fifty-six men reported for duty. A portion of two companies were upon the skirmish line, when the rest of the regiment moved for the field, and consequently did not accompany it.

Of those who crossed the river, less than five hundred in number, two hundred and twenty-six, nearly one-half, were either killed or wounded. Captains Wood, Mason, and Brown, and Lieutenants Clay, Brown, Carroll, Vincent, Riblet, and Hubbard, nine commissioned officers, were either killed or mortally wounded. Colonel Brown received two severe wounds, one of which was supposed to be mortal, but from which he recovered. Captain Lynch, and Lieutenants Long and Stuart, were among the wounded. Colonel Von Shock, of the New York Seventh, and Lieutenant Colonel M'Creary, were the only field officers in the entire brigade who were not either killed or wounded.

After its return to quarters, the regiment was engaged in drill and in picketing the river, from the Railroad Bridge to Franklin's Crossing, below the city.

Elaborate preparations were made during the early spring of 1863, for a campaign, under the leadership of General Hooker. When the army finally moved, the One Hundred and Forty-fifth was detailed to construct corduroy roads, to facilitate the movement of the artillery and heavy trains, and subsequently to assist the engineer corps in laying the pontoon bridge, at United States Ford.