OPERATIONS AT ISLAND NO. 10 AND NEW MADRID--NAVAL BATTLE ON THE MISSISSIPPI--THE BLOODIEST BATTLE WEST OF THE ALLEGHANIES--COMMENCEMENT OF BATTLE OF SHILOH, SUNDAY, APRIL 6, 1862--TERRIBLE LOSSES ON BOTH SIDES--TRAGIC DEATH OF GENERAL ALBERT SIDNEY JOHNSTON--GENERALS WALLACE, HINDMAN, AND GLADDEN KILLED--GENERAL GRANT LEADING A REGIMENT--PUBLIC MISUNDERSTANDING REGARDING THIS GREAT BATTLE--INTERESTING INCIDENTS OF THE FIGHT--FATE OF CONFEDERACY DETERMINED AT SHILOH. When the first line that the Confederates had attempted to establish from the mountains to the Mississippi was broken by the battle of Mill Springs and the fall of Forts Henry and Donelson, their forces at Columbus were withdrawn down the river to the historic latitude of 36° 30'. Here the Mississippi makes a great sigmoid curve. In the first bend is Island No. 10 (the islands are numbered from the mouth of the Ohio southward); and at the second bend, on the Missouri side, is New Madrid. Both of these places were fortified, under the direction of Gen. Leonidas Polk, who had been Bishop of the Protestant Episcopal diocese of Louisiana for twenty years before the war, but entered the military service to give the Confederacy the benefit of his West Point education. A floating dock was brought up from New Orleans, converted into a floating battery, and anchored near the island; and there were also eight gunboats commanded by Commodore George N. Hollins. The works on the island were supplemented by batteries on the Tennessee shore, back of which were impassable swamps. Thus the Mississippi was sealed, and a position established for the left (or western extremity) of a new line of defence. [Illustration: CONSTRUCTING MILITARY ROAD THROUGH SWAMP.]