The next morning the tide turned. Buell's army had come, and fresh troops were poured on the wearied Confederates. Beauregard, obstinately resisting, was driven from the field. He retreated, however, in good order, and, unmolested, returned to Corinth. General Halleck now assumed command, and by slow stages followed the Confederates. Beanregard, finding himself outnumbered, evacuated Corinth, and Halleck took possession (May 30). ISLAND NO. 10.--The Confederates, on retreating from Columbus, fell back to Island No. 10. There they were bombarded by Commodore Foote for three weeks, with little effect. General Pope, crossing the Mississippi in the midst of a fearful rain-storm, took the batteries on the opposite bank, and prepared to attack the fortifications in the rear. The garrison, seven thousand strong, surrendered (April 7) the very day of the conflict at Shiloh. [Footnote: The islands in the Mississippi are numbered in order from the mouth of the Ohio to New Orleans.] [Footnote: Pope, with his army, was on the Missouri side of the river. He could not cross, as the Confederate batteries were planted on the opposite shore. A canal was therefore dug through Donaldson's Point. It was twelve miles long and fifty feet wide. Part of the distance was among heavy timber, where the trees had to be cut off four feet below the surface of the water. Yet the work was accomplished in nineteen days. Through this canal steamboats and barges were safely transferred below the newly-made island, while the two largest gunboats ran the batteries. Under their protection Pope crossed the river.] [Illustration: DONALDSON'S POINT, AND ISLAND NO 10.] _The Effects_ of the desperate battle at Shiloh were now fully apparent. The Union gunboats moved down the river and (May 10) defeated the Confederate iron-clad fleet. On the evacuation of Corinth, Fort Pillow was abandoned. The gunboats, proceeding, destroyed the Confederate flotilla in front of Memphis, took possession of that city, and secured the Memphis and Charleston railroad. The great State of Kentucky and all Western Tennessee had been wrenched from the Confederacy. [Footnote: Besides the results here named, the concentration of troops at Corinth had absorbed the troops from the South. Thus New Orleans, as we shall see hereafter, fell an easy prey to Farragut.] [Footnote: Gen. Halleck having been called to Washington as General-in-Chief of the armies of the United States, General Grant was appointed to the command of this army.] The Union army now held a line running from Memphis, through Corinth, nearly to Chattanooga, toward which point General Buell was steadily pushing his troops. We shall next consider the efforts made by the Confederates to break through this line of investment. At this time they were concentrated under Bragg at Chattanooga, Price at Iuka, and Van Dorn at Holly Springs.