It was not until the twelfth of November, 1862, that General Grant was set free to do those things which it was necessary to do in this quarter of the country. On that date he received a dispatch from General Halleck, giving him command of all troops in his department, and authorizing him to conduct operations there on his own judgment. Thus armed with liberty to act, Grant instantly consulted Sherman, in whose sagacity and in whose superb fighting qualities he had the utmost confidence. These two energetic commanders quickly agreed upon a plan of action which looked to nothing less than the capture of Vicksburg and Port Hudson, the opening of the great river throughout its length, and the severance of the Confederacy in twain.
Their plan at first was that Grant, with about 30,000 men, should move against the Confederate General Pemberton, who had about an equal force in the Tallahatchie river country, and occupy him there while Sherman, with 30,000 more, should descend the Mississippi in transports, convoyed by the gunboats, and effect a landing within striking distance of Vicksburg. Should Pemberton fall back for the defense of that stronghold, Grant was to press him with all possible vigor, endeavoring to cut him off from Vicksburg, and leave Sherman free to deal with that fortress as he pleased.
The Tallahatchie country, through which Grant marched to assail Pemberton, is a tangled wilderness, lying actually lower than the surface of the Mississippi, and itself laced by multitudinous rivers, creeks, and streams, all of them difficult of passage, even at times of lowest water, and impossible of passage when a rain or a break in a Mississippi levée suddenly raises them to flood height. The region is, in fact, a vast morass. In parts of it the planters were often left for six, eight or ten months without communication with the outer world, except by way of the rivers themselves, during the winter. It is not difficult, even for the reader who has no technical knowledge of war, to understand how slowly and painfully a march through such a country must be made, when not only the cannon but a wagon train, carrying every ounce of supplies necessary for 30,000 men must be dragged at every step through a quagmire.
But this was not Grant's chief difficulty. With his headquarters at Holly Springs, and a purpose to press forward in a southwesterly direction, he must maintain a long and attenuated line of communication with his base at Columbus, Kentucky. The Confederates were alert and ceaselessly active in assailing this line and rendering it hopelessly insecure. They sent heavy cavalry detachments under Van Dorn and Forrest to cut him off from his base, and Van Dorn, emboldened by repeated successes at last on the twentieth of December assailed Holly Springs itself, where Grant had accumulated many million dollars' worth of supplies in preparation for his campaign. The Confederate cavalrymen captured the town and its garrison, burned all the stores and destroyed the railroad buildings. In the meanwhile Forrest raiding farther north cut the railroad between Jackson, Tennessee, and Columbus, Kentucky, thus completely severing Grant's line, and leaving him in the enemy's country without supplies or the means of procuring them.
In order to save his army Grant immediately abandoned his plan of campaign and moved northwestward to Memphis. His purpose now was to join Sherman there, unite the two wings of the army, and in company with Sherman and the gunboats move down the river and assail Vicksburg in overwhelming force.
But when Grant reached Memphis Sherman had already gone down the river in his transports, accompanied by Porter's gunboats, to a point called Milliken's Bend. There on Christmas day Sherman had landed on both sides of the river, sending the main body of his troops up the Yazoo, which empties from the northeast into the Mississippi near that point. He did this in order to assail the Confederates on the bluffs north of Vicksburg.
At this point a little topographical explanation seems necessary. Vicksburg lies on a great easterly bend of the river. It is perched upon high bluffs which extend thence northward to the Yazoo, striking it at a point called Haines's Bluff.
From Milliken's Bend above Vicksburg Sherman had sent a brigade down the western side of the river to cut the railroad leading from Shreveport, Louisiana, to that city. Landing his main force under the bluffs on the Yazoo, he hoped to march southward in the rear of Vicksburg, and cut the railroad which leads thence to Jackson, Mississippi, the state capital, about fifty miles away. If he could accomplish this he would have Vicksburg isolated from communication on either side of the river.
In all this he was instantly and completely baffled. Low grounds bordered the Yazoo at the point of landing, while the Confederates occupied and had cannon-crowned the bluffs at a little distance from the stream. The flat lands with their marshes were pestilential to the young men of the northwest who constituted Sherman's army. At times of high water the lowlands were often overflowed to a depth of ten feet. They were at all times malarial, and such water as could be had by digging a foot or two into the mucky soil was simply poisonous for human beings to drink. On the other hand, the Southerners on the bluffs above were living in much more salubrious conditions. They had the advantage also of being immune by lifelong use to the miasms which laid so many of the Northern soldiers low. It is scarcely too much to say that the spores of miasmatic disease were at this time more important to the Confederates as a means of defense than their powder and bullets were.
Still further, Sherman had been misled and misinformed with regard to the character of the bluffs which he must assail. He had supposed them to be easily accessible to such lithe young fellows as those northwestern boys who constituted the pith and marrow of his army. He found them instead scarcely more accessible than the steeps of Gibraltar itself. And as at Gibraltar, so at this point the men standing upon the defense not only occupied the heights, but held their bases with a bristling row of well-served cannon, strongly supported by an infantry as good as any that ever fought. The approaches across bayous and creeks and broad marshes were narrow and difficult. The Confederates had fully made good their deficiency in numbers by so planting their cannon and their riflemen as to command these approaches completely.