The United States Army had just 16,000 men at the onset of the Civil War. A majority of the officer was West Point-trained and had served in various posts around the country. Many of the men who were called upon to lead the large armies that both sides built had commanded companies in their former assignments.
In fact, the only serving officer who had commanded a large force was Brevet Lt. Gen. Winfield Scott, who had commanded 4,000 men in the invasion of Mexico in 1947. Scott was the pioneer of the turning or flanking maneuver that he used to good advantage against the Mexicans. Ulysses S. Grant and William T. Sherman perfect this tactic during the war.
General Albert Sidney Johnston, who was killed at Shiloh, commanded the 2nd Cavalry in Texas. Robert E. Lee was his second-in-command. Lt. Gen. Richard S. Ewell said that the U.S. Military Academy taught officers everything that they needed to know about commanding a company of dragoons on the frontier. It is no wonder that the pre-war course on strategy and the art of war lasted no more than a week. More time was spent on horsemanship because the army expected their officers to spend most of their careers in the saddle.
Many officers had no experience commanding troops in any type of fighting. Some failed and caused tremendous casualties among their men. Other succeeded purely on natural ability. Men who had led no more than companies were now called upon to lead regiments, brigades, divisions and corps.
Joshua Lawrence Chamberlain had been a college professor before the war. He learned all of the tactics required for commanding infantry from books. At Little Round Top on July 2nd, he proved that his education was successful when his 20th Maine turned back repeated attempts by the 15th and 47th Alabama who were attempting to turn the Union position.
Maj. Gen. Ambrose Burnside behaved like a regimental commander but was a dismal failure at commanding an army. His disasters at Fredericksburg and the “Mud March” were an excellent example of his lack of ability. He was somewhat better as a corps commander. “Fighting” Joe Hooker was another Union commander who found his niche as a corps commander after his disastrous defeat at Chancellorsville.
On the Confederate side, Robert E. Lee was a failure in western Virginia at the start of the war. His record was so dismal that he was relegated to the backwater of the Coastal Command in North and South Carolina. His rise to command of the Army of Northern Virginia was purely by chance after Gen. Joseph E. Johnston was severely wounded at the Battle of Seven Pines. Lee happened to be Jefferson Davis’ military adviser and was the right man at the right place.
Lt. Gen. Thomas J. Jackson, the great “Stonewall”, had been a college professor at the Virginia Military Institute when the war began. Called upon to train Virginia militia troops, Jackson rose on sheer ability. His Valley Campaign of 1862 is still studied at West Point. He was mortally wounded by his own troops at Chancellorsville but not before crushing the Union Army was a daring flank attack, considered the greatest ones of the war.
Commanders on both sides were generally indifferent to European military theory from men like Baron Antoine-Henri Jomini and the Prussian General Carl Von Clausewitz. Commanders during the Civil War were called upon to be innovative rather than having a great reliance on theory.
The goal of generals during the war was quite simply to destroy the other side’s force. Using as much firepower as they had available, both armies literally flung themselves at each other. Early in the war they did this with little skill. Their armies were simply armed mobs who charged indiscriminately at each other. It was only after the troops and their generals became more skilled did we see maneuvers like the flank attack.
The steep learning curve encountered by generals was only overcome after a great loss of life and futility on the battlefield. In the early war the battles either had very few casualties or many casualties. In the engagements leading up to the First Battle of Manassas (or Bull Run) casualties were never more than 100 on either. At Manassas the Union Army sustain 2,986 killed, wounded or missing while the Confederates had about 1,000 fewer casualties.
The classic Valley Campaign was a true illustration of how a gifted commander could out-maneuver and defeat his enemy. “Stonewall” Jackson led a force of 17,000 men over 646 miles in 48 days and won several minor battles as they successfully engaged three Union armies (52,000 men), preventing them from reinforcing the Union offensive against Richmond.
Ultimately, the classroom for generals on both sides of the war was the battlefield.