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  • James Houser

July 4, 1863 - The Siege of Vicksburg

Updated: Jun 12, 2021

July 4, 1863. Under the guns of Ulysses S. Grant’s Army of the Tennessee, 30,000 Confederate soldiers lay down their arms in the trenches in front of Vicksburg. The last major Confederate strongpoint on the Mississippi River is in Union hands, and the South is split in two. More than any other event, the Vicksburg Campaign solidifies Grant’s reputation as Lincoln’s top general – and strikes the first mortal blow to the Rebel cause.

In summer 1861, when the war was new and the blood was barely dry on the Bull Run battlefield, Ulysses S. Grant had been working the front desk of his father’s dry goods store when he received his commission as a Brigadier General. Weeks later he was in command of the Union forces at Cairo, Illinois, the spot where the Mississippi and Ohio River join – a dagger aimed at the seam of the South.

Grant, even in those early, confusing days, knew what the Union’s strategy had to be to win the war. As he pondered possible plans of campaign with his staff, he quietly traced the courses of three major rivers: the Cumberland, which flowed from Nashville; the Tennessee, which made a great arc through Tennessee, Alabama and Kentucky to join the Ohio only a few miles above Cairo; and finally, of course, the mighty Mississippi, the largest river in America, that flowed from Cairo itself down to New Orleans and the ocean.

Grant recognized that these three rivers were the weak points in the Confederate defense. The Union was building a river fleet, and the dominance of these rivers could allow Union armies to strike deep into the heart of the South and – most importantly – stay there. Rather than marching overland, where their supplies would be vulnerable to raids and guerrillas, and they would have to leave thousands of troops to hold each mile of ground they covered, the North could cruise down the rivers and dominate the great cotton lands of Mississippi and Tennessee. In a sense, these were the seams by which the Union could cut the South apart.

From 1861 on, Grant pursued this strategy. The first victories that brought him to national eyes – the capture of Forts Henry and Donelson in February 1862 – opened the Cumberland and Tennessee Rivers to Union gunboats. Less than a year after the South had fired on Fort Sumter, a small Yankee flotilla was terrorizing northern Alabama on a daredevil raid up the Tennessee River. Nashville fell without a fight, and West Tennessee was irrevocably lost. Grant had captured 18,000 Confederate soldiers at Fort Donelson, and even the terrible, bloody battle at Shiloh (April 6-7) on the Tennessee could not disguise the fact that the North had achieved virtual control over two out of three of the critical rivers.

The Mississippi was the hard one. After Grant had beaten the Confederates at Shiloh and ended that threat for a while, Union gunboats had seized Memphis, Tennessee and Grant made his headquarters there. Union fleets also seized New Orleans in April, and Admiral David Farragut’s triumphant fleet steamed up the Mississippi to try and join Grant – but ran into a major problem very quickly. As they ascended the great river, they ran into a major Confederate gun battery on a high cliff. Just north of this cliff was the city of Vicksburg.

Vicksburg was about to become Ulysses S. Grant’s obsession for the next year. With Memphis and New Orleans both in Union hands, only Vicksburg prevented the Northern fleets from controlling the whole Mississippi. Vicksburg became the linchpin holding the Confederate train together. Vast amounts of food and supplies passed over the Mississippi at Vicksburg to feed and supply Lee’s army in Virginia and other Rebel armies in Tennessee. Large amounts of arms, equipment and ammunition came that way too, bought by Confederate agents from the French occupiers of Mexico and transported through Texas and Louisiana. Cotton went the other way, harvested from the rich plantations of Alabama and Georgia to be smuggled out through the ports of Texas. Take Vicksburg, and all this would end. The Confederacy would be cut in two.

It was not as easy as marching an army down there. Grant needed more men badly; he was barely able to hold the ground he had taken in West Tennessee and northern Mississippi from Confederate raiders like Nathan Bedford Forrest. It took a large number of soldiers to hold the railroad, and they had to be everywhere all the time – while the Confederates could hide within the friendly population, and attack anywhere at any time. At every point of the Vicksburg Campaign, about half of Grant’s troop strength was tied down protecting his supply lines.

Even if he did manage to start a campaign against the fortress city, Vicksburg is 250 miles from Memphis, and bounded by impassable swamps to the north. If Grant had trouble holding his supply lines now, how bad would it be as he marched south, only getting weaker the whole time?

He tried it, though. In December 1862 Grant, having finally scraped together enough men to launch an attack, decided on an ambitious pincer movement. He would march one half of his army south through the interior of Mississippi, while his trusted subordinate William T. Sherman would take a second force down the river on steamers and gunboats. The plan was that Grant would draw the main enemy army to come fight him in Mississippi, while Sherman slipped behind to take the unprotected city.

Sadly, it didn’t work. Confederate cavalry destroyed Grant’s railroad supply lines whenever he tried to move forward into Mississippi, and he was forced to turn back, only to learn unhappily that Sherman had already left. Sherman suffered a bloody defeat when he attacked the – unbeknownst to him - fully manned defenses of Vicksburg, and had to lead his men in a fighting retreat back to the boats. Grant reunited the two halves of the army, sadly demoralized, at a camp on the banks of the Mississippi.

Many other Union generals would have been discouraged by this failure, and in Grant’s shoes most others would have whined to Lincoln about how they didn’t have enough troops, or tried to find some other, easier target. But Grant saw the objective, knew it had to be taken, and accepted the failure. That way didn’t work. He would try another way.

As the newly dubbed Army of the Tennessee drilled and trained in the sticky southern spring, Grant and Admiral David D. Porter tried plan after plan to isolate and capture Vicksburg. At this point, the operation was as much an engineering problem as it was a military one. How could they take the city? Going at it directly from the river was obviously out of the question; Sherman had tried that once and there was no reason to think a second try would go any better. Marching overland couldn’t work; the more troops Grant had to drop off to watch his supplies, the weaker his army would get and the stronger the enemy would get – as he had seen in December 1862.

Grant and Porter explored many options:

1. Why not dig a canal to try and bypass Vicksburg on the west side of the river? This was Porter’s idea, encouraged by Lincoln. Grant shrugged and put the men to work on it. If it worked, great; if not, it kept them in shape and gave them something to do. It didn’t work.

2. Why not blow up the Mississippi levee and flood out portions of western Mississippi, allowing Union supply ships to float to the hills northeast of Vicksburg? Grant tried this route, but the low-hanging trees caught many of the gunboats and the Confederates built a fort on the hills before Porter’s ships found a good route. Grant gave up on this by early April.

3. Why not go up the Yazoo River, past the new fort, to land troops on the dry ground near Yazoo City? Grant tried this and almost lost his fleet when Porter’s gunboats became stuck. Confederate troops felled trees to trap the ships in the shallow water, and cavalry almost managed to capture the stuck gunboats. Sherman had to lead amphibious assaults to rescue Porter’s ships. No one was in a hurry to try this again.

All these options failed, but Grant was the Thomas Edison of generals: he hadn’t failed, he’d just found a bunch of ways that wouldn’t work. His final option was extremely bold, but extremely risky: march the Army of the Tennessee down the west side of the river opposite Vicksburg, sneak Porter’s ships past Vicksburg in the dead of night, cross the river SOUTH of the city (deep in hostile territory), and march on the Confederates from their rear. This was an enormous gamble, because if it failed Grant’s men could be cut off miles from any supplies or support and possibly wiped out.

Most of Grant’s subordinates and superiors – even Sherman – protested that this was lunacy. Grant would be isolated from his supply lines, and marching deep into Mississippi without communications with any other Union force or even the capital. Grant, though, had had a revelation. By worrying about his supply lines this whole time, he had only bound himself to a vulnerable thread. By letting go of the thread – abandoning his supply lines for a short time and living off the land – he could move faster and strike with more men than before. It was risky, aggressive, and flew in the face of all military science and doctrine.

When Washington’s bureaucrats and desk generals sent alarmed messages urging him not to be so rash, Grant basically stuck his fingers in his ears and carried out his plan.

As the Army of the Tennessee wound its way down a carefully constructed road, Porter’s gunboats and transports ran the Vicksburg batteries with only light losses. Linking up south of the city, Grant ferried his army across and struck out into the heart of Mississippi. Washington D.C. would not hear from him for almost two weeks.

Grant struck fast, and hard, beating two isolated Confederate forces. When the main Confederate army under John Pemberton, based in Vicksburg, called for reinforcements from Tennessee, Grant moved like lightning and headed off these reinforcements before they could save the Southern army. Then he pivoted and within 48 hours was fighting Pemberton, beating him and driving him back into the defenses of Vicksburg at the Battle of Champion’s Hill.

If the Confederates had put all their forces together, they would have greatly outnumbered Grant, but his abandonment of the supply chain freed him to move as fast as he wanted, defending nothing and attacking quickly. He used this speed to divide and conquer, beating the separate forces before they could unite against him. His troops lived off the land, raiding the larders of big plantation houses and seizing the livestock of the Mississippi countryside.

By May 18, Grant had won five battles and trapped Pemberton’s 30,000 men inside Vicksburg. Grant’s gunboats waited north and south of the city, and his troops had the Confederates with their backs to the river. After a couple of failed assaults on the fortress town, including several mines exploded beneath the Confederate earthworks, Grant settled down to starve the Confederates out. It was only a matter of time.

Pemberton sent a messenger to Grant on July 3, the day Pickett’s Charge was taking place, far away at Gettysburg. Grant and the hapless Pemberton met on July 4 beneath an old oak tree and agreed that the entire Southern army would march off into parole, only to take up arms again when exchanged for Union prisoners. In reality, Grant knew his army was unprepared to deal with 30,000 prisoners, and rightly guessed that most of the Southern troops would desert and never return to the ranks.

Grant’s victory at Vicksburg came right after Lee’s defeat at Gettysburg, but was far more important. It split the Confederacy in two down the Mississippi; Arkansas, Louisiana and Texas were now permanently isolated from the rest of the South. It removed an entire Confederate army from the board at a time when they could not really afford to lose more men – and Grant had suffered only 10,000 casualties in exchange for 30,000 surrendered Rebels and 10,000 enemy killed and wounded. These were not winning odds for the South. Grant was undefeated, with a veteran Army of the Tennessee – the best army the Union produced in the war – at his back.

After a year of failed expeditions, ideas that didn’t pan out, and misadventures, Grant had achieved a spectacular success in the Vicksburg Campaign. It was the most brilliant campaign of the whole war, and possibly of the century. Grant’s skillful use of maneuver, willingness to abandon the textbook when needed, army-navy cooperation, flexibility and inventiveness had brought the Union to victory in the decisive campaign of the war, catapulting him into the first rank of Union generals and eventually earning him the top command. Lincoln had him marked. Old Abe had found his general.

On a side note, someone else was taking notes from Grant’s campaign. His subordinate William T. Sherman, who believed it couldn’t be done, came to realize that a large army could live off the land, with no supply lines or communications, for a long period, and his mind was now open to the possibilities. He would take this method to the logical extreme in a year – with an army twice as large, over an area five times as broad – when he marched through Georgia in 1864.

If the Confederacy had been willing to listen, they could have heard their death knell on July 4, 1863.

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