cers gained experience as division commanders. He also delayed the organization of army corps for political reasons. Over one-half of his division commanders were Republicans who were ardent supporters of Lincoln, while McClellan, a political foe of the president, was a Democrat. In March 1862, before the Peninsula campaign began in Virginia, Lincoln, concerned about command and control in combat, directed that McClellan's forces be organized into army corps. McClellan organized the Army of the Potomac on the peninsula into four army corps of three divisions each. The Union forces on the upper Potomac were also placed into an army corps.[1]
Combat experience brought organizational changes to the Army of the Potomac. Cavalry assigned to divisions within army corps were generally unable to perform army-level missions. In July 1862, after the Peninsula campaign, Brig. Gen. George Stoneman, Chief of Cavalry of the Army of the Potomac, shifted cavalry units from the infantry divisions and organized two cavalry brigades for the army, but he left a cavalry squadron[2] in each army corps for picket, scout, and outpost duties. Little improvement resulted from having separate cavalry brigades, which were used the same as the cavalry squadrons in the army corps.
In November 1862 Maj. Gen. Ambrose Burnside took command of the Army of the Potomac and reorganized it into three "grand divisions." He planned for each grand division to move and fight as a heavy column of two corps and a cavalry division, which removed the cavalry from army corps. The grand division commanders, however, were reluctant to use cavalry as an independent force. In February 1863 Maj. Gen. Joseph Hooker, the new commander of the Army of the Potomac, abolished the grand divisions and reverted to the army corps structure. At the same time the Union cavalry was also reorganized as a separate corps under Stoneman, with approximately 13,000 men divided into three divisions. Each division had two brigades, with each brigade having three to five regiments. Artillery was assigned to the cavalry corps headquarters. The cavalry corps operated as an independent unit thereafter, but the jest "Whoever saw a dead cavalryman?" remained within the Army of the Potomac.[3] By June 1863 Union cavalry proved equal to the Confederate cavalry. At Brandy Station the Union cavalry corps excelled under the aggressive leadership of Maj. Gen. Philip H. Sheridan in 1864.[4]
Experience also led to the standardization of field artillery pieces and their massing within the army corps. At Manassas the Union artillery had been assigned to brigades, but when organizing the Army of the Potomac McClellan assigned it to divisions, usually one artillery battalion per division. He also approved a ratio of 2.5 artillery pieces to 1,000 infantrymen, with six artillery pieces of the same caliber, if possible, forming a battery. One of every four batteries was to be a Regular Army unit, the commander of which was to assist the division commander in organizing and training the artillery. Because of the shortage of artillery pieces in 1861, the Union's arsenals were ransacked and guns of various calibers were sent to the troops in the field, causing ammunition and supply problems. But eventually the Army of the Potomac achieved
- ↑ Robert M. Epstein, "The Creation and Evolution of the Army Corps in the American Civil War," Journal of Military History 35 (Jan 1991): 21–46; OR, 5:11–67 passim, Congress provided for army corps on 17 July 1862.
- ↑ A cavalry squadron was and still is equivalent to a battalion.
- ↑ Philip H. Sheridan, Personal Memoirs of P.H. Sheridan, General of the United States Army, 2 vols. (New York: Charles L. Webster & Co., 1888), 1:347.
- ↑ Ibid.; B. W. Crowninshielf, "Cavalry in Virginia During the War of the Rebellion," Journal of the Military Service Institution 12 (May 1891): 527–31; Kenneth P. Williams, Lincoln Finds a General, 4 vols, (New York: Macmillan, 1949), 2:483, 487; OR, 25:471–72; Moses Harris, "The Union Cavalry," Journal of the U.S. Cavalry Association 5 (Mar 1892): 2–16.
