But the greatest of the operations leading down to 1864 were in the West Central States. At the beginning of 1862 the National commanders set out to regain possession of the Mississippi River. In January General Thomas defeated the Confederates at Mill Spring. In February Commodore Foote reduced Fort Henry, on the Tennessee River. A few days later General U. S. Grant, after most severe fighting, captured Fort Donelson and its garrison of 15,000 Confederate troops. This was the first really great Union victory, and Grant at once became a dominant figure in the drama of civil war. Other operations followed, by which the Confederates were driven out of Kentucky, and largely out of Tennessee. In April General Pope and Commodore Foote captured Island No. 10, with 7,000 Confederates, thus clearing the Mississippi down to Memphis. Early in April a great two days’ battle was fought at Pittsburg Landing, on the Tennessee River, Generals Grant and W. T. Sherman commanding the National army, and A. S. Johnston and G. P. T. Beauregard the Confederates. On the first day the Confederates were successful, but on the second the National army rallied, regained its ground, and drove the foe before it in one of the bloodiest conflicts of the war. General A. S. Johnston was killed--an irreparable loss to the Southern cause. The Union armies now moved southward into Alabama and Mississippi. Early in 1863 they gathered about Vicksburg, the “Gibraltar of the South,” the only important obstacle to the reopening of the Mississippi. Admiral Porter co-operated with his fleet. A long siege, marked by many desperate engagements, followed, ending with the surrender of Vicksburg, with 27,000 men to General Grant. This occurred on July 3d, at the very time when Meade was putting Lee to rout at Gettysburg. A few days later Port Hudson surrendered to General Banks; Admiral Farragut, in a naval conflict of surpassing splendor, had already captured New Orleans; and thus the entire Mississippi was regained by the National authorities. Later, a great reverse was suffered. General Rosecrans was terribly beaten by the Confederates at Chickamauga, and driven into Chattanooga, where he was besieged. This was on September 19th and 20th. But Grant was now free to turn his attention thither, and he quickly drove the Confederates away from Chattanooga southward into Georgia.