Meantime every effort was made to strengthen the force under the command of General Grant. He had already ordered a division under General Lanman, and four regiments at Memphis to join him. He now brought forward the divisions of Generals Smith and Kimball, of the Sixteenth army corps, and placed them under the command of Major-General C. C. Washburn. On the 11th of June, Major-General F. J. Herron’s division, from the department of Missouri, arrived, and on the 14th, two divisions of the Ninth army corps, Major-General J. G. Parke commanding, reached Vicksburg. These two divisions were a part of the forces of General Burnside, commanding in the Department of Ohio. This increase of the forces of General Grant enabled him to make the investment of Vicksburg more complete, and at the same time left him a large reserve with which to watch the movements of General Johnston. These reinforcements were arranged by placing General Herron’s division on the extreme left, south of the city. General Lanman’s division was placed between Generals Herron and McClernand. General Smith’s and General Kimball’s divisions, and the force under General Parke, were sent to Haines’s Bluff. This place was now fortified on the land side, and every preparation made to resist a heavy force. About the 25th of June, General Johnston crossed the Big Black river with a portion of his force, and everything indicated that he would make an attack. About this time Rear-Admiral Porter reported to Secretary Welles, under date of May 27, the loss of one of the finest gunboats in his fleet, in the following dispatch: SIR:—Amidst our successes I regret to report any losses; but we cannot expect to conquer a place like this without some loss. At the urgent request of Generals Grant and Sherman, I sent the Cincinnati to enfilade some rifle pits which barred the progress of the left wing of our army. General Sherman supposed that the enemy had removed his heavy guns to the rear of the city. On the contrary, he seemed to have placed more on the water side than usual. The Cincinnati was sunk in shoal water, with her flag flying. The enemy still continued to fire upon her, but the flag was not hauled down. Twenty-five were killed and wounded, and fifteen are missing. The latter are supposed to be drowned. The vessel can be raised. The pilot was killed early in the action. DAVID D. PORTER, Acting Rear-Admiral, Commanding Mississippi Squadron. A successful naval expedition to Yazoo city, is thus described in the report of Rear Admiral Porter, under date of May 24: