The battery is referenced on a War Department marker at Antietam and honored by two monuments at Gettysburg.

1861
January At Fortress Monroe, Va.
May 22 Attached to the newly-created Department of Virginia
June 10 Action at Big Bethel, Va.
August 28-29 Capture of Forts Hatteras and Clark, Hatteras Inlet, N. C.
September Ordered to Washington, D.C., and attached to Artillery Reserve, Army of the Potomac
1862
March Moved to the Virginia Peninsula.
April 5-May 4 Siege of Yorktown
May 4 Near Williamsburg
May 9 Sistersville, New Kent Court House
May Consolidated with Battery “L” 2nd United States Artillery and attached to 1st Brigade, Horse Artillery, Artillery Reserve, 5th Army Corps, Army of the Potomac
June 25-July 1 Seven days before Richmond
June 30 Turkey Bridge
July 1 Malvern Hill
July At Harrison’s Landing
August 16-24 Moved to Fortress Monroe, thenc to Alexandria
September 6-22 Maryland Campaign. Attached to Pleasanton’s Cavalry Division, Army of the Potomac
September 10-11 Sugar Loaf Mountain
September 12 Frederick, Md.
September 13 Catoctin Mountain
September 16-17
Battle of Antietam

The battery was commanded by Captain James M. Robertson. It was armed with four 3″ Ordnance Rifles.

From the War Department marker at Antietam:

Horse Batteries B and L (consolidated), 2d U.S. Artillery, crossed the Antietam by the Middle Bridge in the forenoon of September 17, and went into position on a knoll 80 yards south of this point and engaged the enemy. It was soon disabled by the fire of the Confederate Artillery from Cemetery Hill and withdrawn, its position being taken by Battery E, 1st U.S. Artillery. One section of the Battery, under command of Lieut. Albert 0. Vincent, moved to the northwest about 860 yards and engaged a Confederate Battery posted in the northern part of Piper’s Orchard. The Battery was withdrawn before dark and returned to its bivouac near Keedysville.

September 19 Shepherdstown Ford
November 4 Markham Station
November 6 Warrenton
November Attached to Averill’s Cavalry Brigade, Right Grand Division, Army of the Potomac
December 12-15
Battle of Fredericksburg

1863

February Attached to 1st Division, Cavalry Corps, Army of the Potomac
April 27-May 8 Chancellorsville Campaign
April 29-May 8 Stoneman’s Raid
June Attached to 1st Brigade, Horse Artillery, Army of the Potomac
June 9
Battle of Brandy Station 

Commanded by Lieutenant Edward Heaton.

July 1-3
Gettysburg

The battery was commanded by Lieutenant Edward Heaton. It battery was armed with six 3 inch Rifles.

From the monument in Gettysburg on Pleasonton Avenue:

July 2. Arrived near the battlefield at 5:30 a.m. and reported to Major General Alfred Pleasonton who ordered the Battery be held in reserve until near dark when it was moved back two miles on the Baltimore Pike for the night.

July 3. Moved to the front and was ordered to the position occupied the day before but being subject to the severe artillery fire the Battery was ordered to retire out of range and there remained until the close of battle.

From the monument in Gettysburg on Granite Schoolhouse Lane:

July 2 Arrived at 5.30 A.M. In reserve during the day and at night withdrew two miles on the Baltimore Pike.

July 3 Advanced to former position in the morning and ordered to the Reserve Artillery and for a time exposed to a severe fire. In the evening was withdrawn to the position of the previous night.

August 1-4 Brandy Station
September 13-17 Advance from the Rappahannock to the Rapidan
October 9-22 Bristoe Campaign
October 10 Raccoon Ford
October 11 Morton’s Ford, Stevensburg, and Kelly’s Ford
October 11-12 Brandy Station or Fleetwood
October 15 Oak Hill
November 7-9 Advance to line of the Rappahannock
November 26-December 2 Mine Run Campaign
November 27 New Hope Church
May 4-June 12 Rapidan Campaign
1864
May 5-7
Battle of the Wilderness
May 6 Brock Road and the Furnaces
May 7-8 Todd’s Tavern
May 9-24 Sheridan’s Raid to the James River
May 11
Yellow Tavern and Ground Squirrel Church
May 12 Brook Church or Richmond fortifications
May 26-28 On line of the Pamunkey
May 27 Hanovertown
May 28 Crump’s Creek and Haw’s Shop
May 28-31 Totopotomoy
June 1-7
Cold Harbor
June 16-August 5 Siege of Petersburg
July 27-29 Deep Bottom
August 7-November 28 Sheridan’s Shenandoah Valley Campaign
August 11 Tell Gate, near White Post, and near Newtown
August 16 Cedarville, Guard Hill or Front Royal
September 19
Third Battle of Winchester (Opequan)
September 20 Near Cedarville
September 21 Front Royal
September 22 Milford
September 29 Waynesboro
October 8-9 Tom’s Brook
October 19
Battle of Cedar Creek
December Attached to Reserve Artillery, Middle Military Division
December 19-22 Expedition to Lacey Springs
1865
January Duty in the Shenandoah Valley
April Duty at Washington, D.C. attached to Horse Artillery Brigade, 22nd Corps until August