Battery a, Fourth United States Artillery.Battery A, Fourth United States Artillery, was one of the celebrated horse batteries of the Army of the Potomac. These photographs, taken by Gardner in February, 1864, represented its four 12-pounder light brass Napoleons “in battery,” with limbers and caissons to the rear, and the battery wagon, forge, ambulance, and wagons for transportation, embracing the entire equipage of a light battery in the field. At that time the battery was on the line of the Rappahannock. Three months later it accompanied Sheridan on his famous Richmond raid, and on the night of May 12th its members heard men talking within the fortifications of Richmond, dogs barking in the city, and bought copies of the Richmond Inquirer from a small but enterprising Virginia newsboy who managed to slip within their lines with the morning papers. Below, beyond “A,” another battery is seen in camp. The horses hitched in, and the open limber-chests indicate an approaching inspection. These formed part of Lieutenant-Colonel James Madison Robertson's brigade.