When Beauregard wisely, and indeed under strategic compulsion, withdrew the forces from Columbus, Kentucky, he sent some of the troops constituting the garrison and most of the guns that bristled from the useless fortifications of that town to New Madrid and Island Number 10, where they were needed.
Early in March General Pope moved down the Mississippi on its western side, and began operations for the reduction of New Madrid. When he had got his siege guns into position and opened a serious bombardment, the works there were quickly abandoned.
Then began the assault upon Island Number 10, the one great northern stronghold of the Confederates in the Mississippi river, designed to hold that great waterway and forbid to the Federals its use as a thoroughfare into the heart of the South.
The Federal army cut a canal across the peninsula formed by the great bend in the river. All the naval force that the Federals could command in those waters was brought to bear not only for the reduction of the forts there but still more for the beating off of the Confederate gunboats under Commodore Hollins. On the other hand Commodore Foote ran the canal with his Federal gunboats and established himself in a commanding position in reverse of the forts while Pope crossed the stream and assailed the enemy in front with all his land forces.
The situation of the Confederates was a hopeless one and after an effort to escape they surrendered nearly 7,000 men and more than 150 guns, most of them of large caliber and formidable destructive force.
This occurred on the second day of the Shiloh battle, April 7, 1862, on which day, after a heroic effort to breast Grant's overwhelming numbers, Beauregard withdrew from Shiloh to Corinth. This capture of Island Number 10 opened the Mississippi to Memphis, except for the single and, as it afterwards proved to be, the utterly ineffective position at Fort Pillow.
General Halleck was fully informed of all that had happened. He knew that Pope's way was open down the Mississippi to Memphis, and that Memphis, scarcely at all defended, was within his easy grasp. He knew of course that Memphis was the westerly end of the new defensive line of the Confederates, and that its capture must compel them still further to retire toward the south, even should he fail or neglect to drive them from the Memphis and Charleston railroad line at Corinth, as he easily might have done with his utterly overwhelming force, and as Grant would undoubtedly have done if that vigorously aggressive general had been left in control of that splendidly equipped army. But Halleck sat still and pottered over "reports" that annoyingly paid no tribute to his genius and suggested no credit to him for the victory that had been won.
Meanwhile Grant was losing time. The Confederates, foreseeing the inevitable loss of Memphis, which happened on the sixth of June, nearly two months after energy would easily have compelled it, were busily fortifying all defensible positions on the river below, especially at Vicksburg and Port Hudson, and thus making necessary one of the most strenuous and one of the bloodiest campaigns of the war, where scarcely any campaign at all would have been necessary but for the fact that a martinet officer, much too "scientific" and too "regular" for the practical purposes of war, was in authority over a man who knew not only how to plan campaigns but how to conduct them quickly to a successful conclusion.