It was by the capture of Fort Donelson, near the mouth of the Cumberland River, that General Grant gained his early fame in the Civil War. The Confederates erected strong defensive works on the two rivers in order to prevent an invasion of Western Kentucky and Tennessee. The places selected were about forty miles south of the Ohio--Fort Henry being built on the eastern bank of the Tennessee River and Fort Donelson on the western bank of the Cumberland, twelve miles apart, and connected by a direct road. A combined land and naval attack was made on these forts in February, 1862, under command of General Grant and Commodore Foote. Fort Henry was easily captured by Foote's gunboats on February 6th after an hour's action, most of the garrison retreating across the neck of land to Fort Donelson. Grant then invested Fort Donelson, being reinforced until he had twenty-seven thousand men, and he attacked so vigorously that after a severe battle on the 15th he effected a lodgement in the Confederate lines and severely crippled them. Part of the garrison escaped southward during the night, and in the morning General Buckner, commanding, asked for an armistice and commissioners to arrange a capitulation. To this Grant made his noted reply, "No terms except unconditional and immediate surrender can be accepted; I propose to move immediately upon your works." Having no alternative, Buckner surrendered. The Union army captured fourteen thousand prisoners, a vast amount of small arms and stores, and sixty-five cannon. Almost immediately afterwards the Confederates practically abandoned Western Kentucky and Tennessee, and Grant moved his army up the Tennessee River, and by the middle of March it was encamped to the westward and along the banks, near the southern Tennessee border, the lines extending several miles from Shiloh Church to Pittsburg Landing. The Confederates under A. S. Johnston and Beauregard were at Corinth, Mississippi, about twenty miles to the southwest. The Union plan was that General Buell, who was coming southwestward from Nashville, should join Grant, and then an advance southward be made. The Confederates, having learned of the plan, early in April decided to attack Grant before Buell could join him, and on the morning of the 6th the onslaught began, the Union army being surprised. This was the great battle of Shiloh, in which the Union forces were pushed back with heavy loss on the first day. Buell arrived, however, crossing the Tennessee that night and joining, so that next day, after a stubborn battle, Grant recovered his position, and the Confederates retreated to Corinth. In this battle the losses were about twenty-five thousand killed, wounded and missing, including three thousand Union prisoners taken.