..., was destroyed by the National gunboat De Soto, Captain W. W. Walker, in the Gulf of Mexico, off Mobile harbor, Ala.--Captain Walker's Report. At daylight this morning the National army, under General Grant , moved on from Champion Hill to the Big Black River, Miss., where a battle was fought with the rebels, under Pemberton, and they were again defeated and driven into their intrenchments around Vicksbu...