American Civil War: The Rise of George B. McClellan


By Gary W. Gallagher, Ph.D., University of Virginia

The advent of George B. McClellan was a major development in the American Civil War. He was General-in-Chief— the commander of all of the Union armies across the entire strategic map of the war—as well as the commander in the field of the Army of the Potomac. Let’s take a look at how McClellan rose to occupy this position.

Illustration of George McClellan riding a horse and passing through a town, while the townsfolk are animatedly greeting him.
George McClellan first replaced Irvin McDowell as the commander of the Union army in the east, and later took over from Winfield Scott as the General-in-Chief of the entire Union Army. (Image: Frank Leslie’s Illustrated Newspaper/Photo Courtesy of U.S. Army/Public domain)

It was the events associated with the Army of the Potomac that made or broke McClellan’s reputation, as we will see. He’s going to be a crucial factor in the war for more than a year, the major Union player on the military side in many ways.

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McClellan Gets Command of Union Armies in the East

Following the disaster at First Manassas in July of 1861, President Abraham Lincoln knew that Irvin McDowell was not the long-term solution to the Northern problem of defeating the rebellion. McDowell had to be replaced, and he was replaced with George B. McClellan. McClellan was given command of that Union army outside Washington, D.C. McDowell was demoted to a division commander.

Old Robert Patterson out in the Shenandoah Valley was eased aside completely. He left the service and retired. So you have a major shake-up in the east of the command structure.

McClellan had won some little victories in western Virginia early in the war. It might be more accurate to say his subordinates had won some little victories in western Virginia, but he got the credit for them, and his reputation rose accordingly. He seemed to be a good choice to command the Union armies in the east.

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Who Was George McClellan?

He was a West Pointer, of course, a very bright cadet at West Point. He’d been sent to Europe as a military observer in the 1850s to study European military theory and practices. He’d fought with distinction in the Mexican War. He was a man who thought about military questions as well as participated in military affairs in the real world.

Full-length portrait of George McClellan in full uniform.
George B. McClellan was a cadet at West Point, following which he was sent to Europe to study European military theory and practices, and even fought in the Mexican War, before joining the Union army. (Image: Mathew Brady/Public domain)

But he didn’t make enough money in the army, or the army wasn’t enough of a challenge for him, and he got out of the army in the 1850s and became a railroad executive. He was very successful at that and made a handsome living in the Midwest.

He was of medium height. You often read that he was short. He wasn’t really short. He was about average height for the time. He had a very barrel-like chest, stood up very straight, and sort of threw his chest out even farther. He was broad-shouldered and had deep-set eyes, a nice thick head of hair, and an aura of command about him. He had what we would call today charisma, I think.

People spoke about George B. McClellan. He’d walk into the room, and people would naturally gravitate toward him. He’s one of those individuals who simply can impose his will on other people or at least get the attention of people that he’s around.

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He would prove to be, without a doubt, the most popular commander of any Union army during the war. His men were absolutely devoted to him. There’s no question about that. In fact, he’s the only Union general who came close to inspiring the kind of blind devotion among his men that the soldiers in the Army of Northern Virginia expressed toward Robert E. Lee for much of the war.

McClellan Becomes General-in-Chief

The Northern press hailed McClellan as the man who would save the Union, and before long that kind of praise went to his head. He came to consider himself not Lincoln’s subordinate, not Winfield Scott’s subordinate, but their superior—the man who knew better than they, his civilian and military betters, so to speak, what was necessary to win the war.

“I’m leaving nothing undone to increase our force,” he wrote to his wife in the early fall of 1861, “but the old general always comes in the way.” He meant Scott. As for Lincoln, McClellan said simply, “The president is an idiot.”

Winfield Scott had had enough of this by late October, as I said—his physical ailments, his aggravation with McClellan—and in early November he very gracefully stepped aside.

McClellan took his place as General-in-Chief. Lincoln was willing—this is one of Lincoln’s strengths we talked about earlier—he was willing to put up with the obnoxious qualities in McClellan’s personality because he thought McClellan would give him victories. Lincoln was willing to put aside his own ego, let this young egomaniac have his rein, and, if he won, the Union would be preserved.

Lincoln did warn McClellan that he was taking on two huge jobs here: You are General-in-Chief of all the armies, and you’re the field commander of our largest United States army. McClellan shrugged that off and said he could do it all. He was a master organizer, and, by the end of September 1861, he’d built the Army of the Potomac into a formidable force of more than 100,000 well-equipped and well-trained men.

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McClellan Overestimated Confederate Strength

Soon after taking over as General-in-Chief, McClellan began to show a pattern that would be with him the rest of the war. He chronically overestimated Confederate strength in his front. He thought there were 150,000 Confederates facing his 100,000 Union soldiers; then he thought there were 200,000. He kept telling Lincoln, I need more men; I need more equipment before I can move.

Well, he overestimated by two or three times how many Confederates were really opposite him, but this is something we’ll see with McClellan again and again. He always inflated Confederate numbers. He always seemed to find an excuse not to move rapidly and not to force the issue militarily.

The bottom line is that McClellan lacked what they would have called, in the nineteenth century, the moral courage to commit this wonderful instrument he had created, the Army of the Potomac, to a decisive contest with the Rebel opponents. He played it safe. He sought perfection, and, as a result, he can never be counted among the great generals of the war.

Common Questions about George B. McClellan

Q: Why was George B. McClellan important to the Civil War?

In July 1861, George B. McClellan was given the command of the Union armies in the East, and later he was promoted to the position of General-in-Chief, the commander of all of the Union armies across the entire strategic map of the civil war. Besides this, McClellan is also known for building the Army of the Potomac into a formidable force of more than 100,000 well-equipped and well-trained men.

Q: What did George B. McClellan do during the Civil War?

George B. McClellan had won some little victories in western Virginia early in the war, which is the reason why he was selected as the commander of the Union armies in the east, when President Abraham Lincoln decided to replace Irvin McDowell. Soon after, Winfield Scott stepped aside and McClellan became the General-in-Chief and began the work of building the Army of the Potomac.

Q: Was George B. McClellan part of the union or confederacy army?

George B. McClellan was part of the Union Army. In fact, he was the General-in-Chief of the Union Army.

Q: Why was George B. McClellan a bad general?

The biggest flaw of George McClellan was that he was a chronic procrastinator. Even though he had built a formidable army in the shape of the Army of the Potomac, he repeatedly delayed proceedings and allowed the Confederates to regroup and bring in reinforcements. He was also guilty of continually overestimating the strength of the Confederate armies.

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