Numbers 22. Report of Major Samuel H. Lockett, c. S. Engineer Corps, chief Engineer Department of Mississippi and East Louisiana, including operations April 3-- May 17. GAINESVILLE, ALA., July 23, 1863.

SIR: I have the honor herein to submit my report of engineer operations during the period included between the dates May 2 and May 18, comprehending the events immediately preceding the siege of Vicksburg.

Having returned from an examination of the works at Grand Gulf on April 30, I received, at Jackson, an order to join the lieutenant-general commanding at Vicksburg, which I did on May 2. The enemy having effected a landing at Bruinsburg, MISS., and forced the evacuation of Grand Gulf on April 30, it became evident that immediate steps would have to be taken to meet him on all available approaches to the city of Vicksburg . The several ferries across the Big Black River and the railroad bridge became points of great strategic importance. I accordingly dispatched an engineer officer to each of these points with the view of establishing works for resisting a passage of the river by the enemy.

On examination it was found that at Baldwin's, hall's and Hankinson's Ferries the bluffs abutted against the river on the east bank, leaving wide bottoms on the WEST, so that at each of these crossings it became necessary to construct a tete-de-pont were ordered, but before anything could be done the army of Grand Gulf, under Major-General Loring, had crossed the river at Hankinson's Ferry, leaving the east band in possession of the enemy. During this time I had gone myself, by the direction of the lieutenant-general, to the railroad bridge and Edwards Depot, to establish works to defend the railroad and preserve this very important line of communication. Having examined the ground, I directed Captain D. Wintter, commanding corps of sappers and miners, to take charge of the construction of a tete-de-pont to cover railroad bridge, and telegraphed to Captain P. Robinson, of the engineers, at Grenada, to report to me at Edwards Depot with all his assistant engineers. Captain Robinson reported on the 9th, and leaving him in charge of the works at the bridge, and directing him to make thorough reconnaissances of the country in the vicinity of Edwards Depot and to the southward, I returned to Vicksburg with Captain Wintter, and put him in charge of all the works around the city, to make necessary repairs and put everything in good condition. The t^ete-de-pont at the railroad bridge was pushed ahead rapidly, and finished by the 15th, and at the same time a bridge was made across the Big Black by swinging the steamer Dot across the stream and removing her machinery.

On the 12th, the army was ordered across the Big Black to Edwards Depot, and I went to the latter place to conduct the DIVISION commanders to the positions assigned to them by the lieutenant-general commanding.

On the 15th, orders were received to march upon the enemy, and I took with me in accompanying the lieutenant-general the following assistant engineers, viz: SECOND Lieutenant George Donnellan, engineers; Captain J. M. Couper and Sergt. McD . Vernon, acting assistant engineers, leaving Captain Robinson and three assistants in charge of the