It was recruited and formed in the summer of 1862 by officers and men of the Anderson Troop, an independent company of the Pennsylvania Volunteers that had been mustered the previous November.

Until the last three months of the war the 15th Pennsylvania Cavalry was an independent unit reporting directly to the headquarters of the Army of the Cumberland, performing escort, scouting, courier and other details for the commanding general.

The regiment of 1100 men in ten companies was raised by officers of the Anderson Troop in July and August 1862 from more than 3,000 applicants representing 30 Pennsylvania counties.

After the first 200 men reported to "Camp Alabama" at Carlisle, Pennsylvania, six companies (B through G) were mustered into United States service by a captain of the regular 1st Cavalry on August 22.

Approximately 400 men, provided horses and carbines, were scattered as pickets, skirmished with Confederates near Hagerstown and participated in the Battle of Antietam, where one trooper was killed.

On November 7, 1862, it left Carlisle by railroad for the Department of the Cumberland under its lieutenant colonel, William Spencer, traveling over a period of three days to Louisville, Kentucky, via Indianapolis, Indiana.

On December 28, Rosecrans took 23 more men from the Anderson Troop previously recommended for commissions and made them temporary officers to address the complaints of the disgruntled soldiers regarding lack of leadership.

Rather than apply duress with the insubordinate soldiers, Morgan used a promise that they would meet with Rosecrans to induce the remainder to leave camp under the command of the lieutenant colonel of the 10th Illinois Volunteers.

That evening however, after encountering a brigade of Wheeler's Confederate cavalry and a battery of artillery blocking the road at La Vergne, they returned to their original camp in Nashville.

In the second engagement, on December 29 at Wilkinson's Cross Roads west of Murfreesboro, its skirmishers were ambushed by Confederate pickets of the 10th South Carolina Infantry, leading to an impetuous mounted charge with carbines by the battalion under Rosengarten.

Stopped by the fence and receiving aimed volleys of musket fire at point-blank range, the regiment quickly lost 11 men killed, 50 wounded and 9 missing.

On New Year's Day it escorted the army's supply wagons back to Nashville, repulsing several attempts by the Confederate cavalry of Gen. Joseph Wheeler to destroy the train.

At Chattanooga the Andersons were initially camped at Cameron Hill, but the loss of their wagons to Wheeler's cavalry while foraging for fodder on October 2 resulted in the 15th Pennsylvania moving to the Sequatchie Valley, where corn, cattle and pigs were plentiful.

Camping near Dunlap in October and Pikeville for the remainder of the winter, the Andersons performed picket duties and gathered forage, particularly beef for the army and corn for its horses and mules.

The scouts made by the Anderson Cavalry were generally conducted at night and the regiment became known among the local, largely Unionist communities as "Palmer's Owls."

On September 13 while at Calhoun, Georgia, it received new orders to return to East Tennessee to locate and intercept the enemy cavalry brigade of John S. Williams.

In four days Wagner's battalion destroyed numerous bridges and reached the outskirts of Lynchburg on the morning of April 8 before turning south to rejoin the main body of Stoneman's force at Salisbury, North Carolina.