General Prentiss also sent an officer to Generals Hurlburt and Wallace, commanding the divisions in his rear, near the Landing, informing them that the Rebels were attacking his pickets in force. The firing increased. The Twenty-first Missouri gave a volley or two, but were obliged to fall back. There had been a great deal of practising at target in the regiments, and every morning the pickets, on their return from the front, discharged their guns, and so accustomed had the soldiers become to the constant firing, that these volleys, so early in the morning, did not alarm the camp. The orders which General Prentiss had issued were tardily acted upon. Many of the officers had not risen when the Twenty-first Missouri came back upon the double-quick, with Colonel Moore and several others wounded. They came in with wild cries. The Rebels were close upon their heels. General Johnston had, as you have already seen, four lines of troops. The third corps was in front, commanded by Major-General Hardee, the second corps next, commanded by General Bragg; the first corps next, commanded by Major-General Polk, followed by the reserves under General Breckenridge. General Hardee had three brigades, Hindman's, Cleburn's, and Wood's. General Bragg had two divisions, containing six brigades. The first division was commanded by General Ruggles, and contained Gibson's, Anderson's, and Pond's brigades. The second division was commanded by General Withers, and contained Gladden's, Chalmers's, and Jackson's brigades. General Polk had two divisions, containing four brigades. The first division was commanded by General Clark, and contained Russell's and Stewart's brigades. The second division was commanded by Major-General Cheatham, and contained Johnson's and Stephens's brigades. Breckenridge had Tabue's, Bowen's and Statham's brigades. General Gladden's brigade of Withers's division was placed on the right of Hardee's line. It was composed of the Twenty-first, Twenty-fifth, Twenty-sixth Alabama, and First Louisiana, with Robertson's battery. Hindman's brigade joined upon Gladden's. Gladden followed Colonel Moore's force, and fell upon Prentiss's camp. Instantly there was a great commotion in the camp,--shouting, hallooing, running to and fro, saddling horses, seizing guns and cartridge-boxes, and forming in ranks. Gladden advanced rapidly, sending his bullets into the encampment. Men who had not yet risen were shot while lying in their tents. But General Prentiss was all along his lines, issuing his orders, inspiring the men who, just awakened from sleep, were hardly in condition to act coolly. He ordered his whole force forward, with the exception of the Sixteenth Iowa, which had no ammunition, having arrived from Cairo on Saturday evening.