The following is taken from New York in the War of the Rebellion, 12th ed. Frederick Phisterer. Albany: J. B. Lyon Company, 1912.

This battery was organized at Albany, January 3, 1862, by the consolidation of the companies recruited by Capts. William H. Ellis and Walter Shaw, and mustered in the service of the United States for three years January 14, 1862. It was recruited principally at Albany, Troy, Newfane, Jordan, Kendall, Wilson, Lockport, Somerset, Amsterdam', Hart-land and Poestenkill. It received its numerical designation January 15, 1862, and at the expiration of its term of service the men entitled thereto were discharged and the battery retained in service. February 18, 1865, a number of men, originally recruited for the 2Oth Battery, at Jamaica, Elmira, Poughkeepsie, Tarrytown and Kingston were assigned to it. The battery, commanded by Captain Ellis, left the State on the I7th of January, 1862, and served at and near Washington, D. C., and in the Artillery Camp of Instruction from January, 1862; in the 22d Corps from February, 1863; in the Artillery Brigade, 3d Corps, Army of the Potomac, from July 7, 1863; in the 2d Brigade, Artillery Reserve, Army of the Potomac, from March, 1864; in the Artillery Brigade, 2d Corps, from May 18, 1864; and in the Artillery Reserve, Army of the Potomac, from September, 1864. Commanded by Capt. Charles A. Clark, it was honorably discharged and mustered out at Albany, June 14, 1865, having lost by death, killed in action, 1 officer, 4 enlisted men; of disease and other causes, 14 enlisted men; total, 1 officer, 18 enlisted men; aggregate, 19; of whom 3 enlisted men died in the hands of the enemy.

The following is taken from The Union army: a history of military affairs in the loyal states, 1861-65 -- records of the regiments in the Union army -- cyclopedia of battles -- memoirs of commanders and soldiers, Volume II: New York, Maryland, West Virginia and Ohio. Madison, WI: Federal Pub. Co., 1908.

Twelfth Independent Battery.—Capts., William H. Ellis, George F. McKnight, Charles A. Clark. This battery was organized at Albany and was there mustered into the U. S. service for three years on Jan. 14, 1862. It continued in service after the expiration of its term as a veteran organization. Commanded by Capt. Ellis, it left the state on Jan. 17, 1862, and was stationed at Washington until the summer of 1863, when it was assigned to the artillery brigade of the 3d corps, with which it participated in the pursuit of Lee's army, after the battle of Gettysburg, being engaged at Wapping heights; was active in the minor engagement at Kelly's ford; took part in the futile Mine Run campaign; and in the same brigade, but attached to the 2nd corps, it fought through the battles from the Wilderness to Petersburg, losing 3 men at Spottsylvania, 4 at the North Anna, i at Cold Harbor, 11 at the Weldon railroad and 11 at Reams' station. From Sept., 1864, it formed part of the artillery reserve. Army of the Potomac, and took part in the final assault on Petersburg, April 2, 1865. It was mustered out under command of Capt. Clark, at Albany, N. Y., June 14, 1865, having lost 19 killed and died of wounds, and by disease.Twelfth Independent Battery.—Capts., William H. Ellis, George F. McKnight, Charles A. Clark. This battery was organized at Albany and was there mustered into the U. S. service for three years on Jan. 14, 1862. It continued in service after the expiration of its term as a veteran organization. Commanded by Capt. Ellis, it left the state on Jan. 17, 1862, and was stationed at Washington until the summer of 1863, when it was assigned to the artillery brigade of the 3d corps, with which it participated in the pursuit of Lee's army, after the battle of Gettysburg, being engaged at Wapping heights; was active in the minor engagement at Kelly's ford; took part in the futile Mine Run campaign; and in the same brigade, but attached to the 2nd corps, it fought through the battles from the Wilderness to Petersburg, losing 3 men at Spottsylvania, 4 at the North Anna, i at Cold Harbor, 11 at the Weldon railroad and 11 at Reams' station. From Sept., 1864, it formed part of the artillery reserve. Army of the Potomac, and took part in the final assault on Petersburg, April 2, 1865. It was mustered out under command of Capt. Clark, at Albany, N. Y., June 14, 1865, having lost 19 killed and died of wounds, and by disease.