It was mustered into the Federal service from July 23 to September 17, 1861, at Philadelphia, for a three years' term under the command of Colonel Ernest G. Chorman.

[2] The regiment spent the winter in the vicinity of the capital in the performance of various routine duties.

[3] On January 17, 1862, the vacancy caused by the retirement of Col. Chorman was filled by the appointment of Capt.

In the Peninsular campaign the brigade was enlarged by the addition of the 1st U.S. Cavalry and was attached to the Army of the Potomac’s (AoP) IV Corps.

In April 1862, the regiment was moved to Blake's Brigade, Cavalry Reserve, Army of the Potomac, to July 1862.

It was present at the Battle of Fair Oaks and active at Malvern hill.

Upon the AoP’s retreat to Harrison's landing, Col. Gregg moved up to the 8th’s cavalry brigade which was employed in heavy picket duties.

[1] On September 4, it was sent to Freedom Hill, encountering the enemy there, at Sugarloaf Mountain and Darnestown.

[4] On the 12th it entered Frederick and drove out the rear-guard of the enemy's cavalry, capturing a number of prisoners.

It then moved on a reconnaissance north into Pennsylvania to Gettysburg,[note 3] captured about 50 more prisoners, and thence marched to the Antietam battlefield, skirmishing on the Sharpsburg Pike on the day after the battle.

00 It remained encamped at Sharpsburg for a time; had a sharp engagement with the enemy at Charlestown; and on October 26, as a part of Pleasonton's cavalry, led the advance of the army into Virginia, being engaged in rapid succession with heavy losses at Philomont, Upperville, Aldie, Barbour's Crossroads, Ashby's Gap, Chester Gap, Orleans, Amissville and Hazel River.

It was next assigned to picket duty at the fords of the Rapidan and Rappahannock, and while in the vicinity of Leeds, a squadron under Capt.

Col. Amos E. Griffiths,[6] the regiment moved to Fredericksburg on the night before the battle and had one squadron engaged on the following day.

Gen. Bayard fell, Col. Gregg took command of the division and was officially notified on the field of his promotion to brigadier general.

[5] The regiment now returned to Falmouth and was employed in scout and picket duty along the Rappahannock, going into winter quarters at Acquia creek about the middle of February 1863.

On May 2, it made one of the most gallant charges in the war, winning for itself the following commendation from Gen. Pleasonton: "The distinguished gallantry of the 8th Pa. regiment, in charging the head of the enemy's column, advancing on the XI corps, on the evening of the 2nd inst., has excited the highest admiration.

* * * The gallant McVikar, the generous chivalric Keenan, with 150 killed and wounded from your small numbers.

It was in action at New Market, losing 15 killed and wounded, and as part of the 2nd brigade, 2nd cavalry division, it moved on the 30th to Westminster, thence to Hanover Junction and on July 4, to Emmitsburg, where it joined the command of Brig.

[5] During the next few days, it was engaged in constant skirmishing in the vicinity of Boonesboro and Jones' cross-roads.

Returning to Virginia, it was engaged in guard and picket duty on the Manassas railroad and at Thoroughfare Gap, and in August it became a part of the 1st brigade commanded by Gen. J. Irvin Gregg.

[5] In the campaign which followed, the regiment was heavily engaged at Sulphur springs, and was again in action two days later at Bristoe Station.

In the advance to Mine Run, it was sharply engaged at New Hope Church and on its return went into winter quarters at Bealeton Station.

During the winter it engaged in raids into the Luray Valley and through Chester gap.

[5] Upon the opening of the Wilderness campaign the 8th participated in the various movements and battles of Sheridan's corps, losing about 100 men on the Richmond raid, 25 at Haw's shop, and 35 at Trevilian Station.

At St. Mary's Church, Gregg's division was attacked by superior numbers, and the 8th again lost heavily, Col. Huey and Capt.

[5] On July 1, it crossed the James with its division, moved to Blackwater, and was engaged on picket duty until the 26th on the Jerusalem plank road.

It then crossed the Appomattox and the James; was in action at Malvern hill, and again on the Charles City road.

About two weeks later it was again engaged at Charles City Road and in August was in action the whole day at Yellow Tavern,[4] where Lieut.

[5] At Reams' station, on Aug. 23, Maj. Wistar was among the wounded and the command devolved on Capt.

It participated in the cavalry operations during the siege of Petersburg and in the spring of 1865, moved with Sheridan to Five Forks, participating in a brilliant campaign which resulted in the surrender of Lee, after which the 8th was ordered to Lynchburg and consolidated with the 16th Pennsylvania Cavalry on July 24.