...ps evacuated the place a few hours previous, and fell back to Covington.--Natchez, Miss., was shelled by the Union gunboats. Yesterday the rebels commenced an attack upon the National forces at Stevenson, Ala. , which continued until to-day, when the rebels retired with a severe loss. The fight was brought on by the National forces, which had just evacuated Huntsville, and were on their way to Nashville, ...