While the fleet and army were at Alexandria, the enemy had passed round the city and appeared on the banks below, where they made the passage of light steamers very dangerous. Two light-draught gunboats, the Covington and Signal, were thus lost to the service. They had gone down convoying a transport called the Warner. The Warner was put in advance, the gunboats following in line ahead. The enemy began with heavy musketry and two field pieces, by which the Warner's rudders were disabled; she continued on a short distance till a bend was reached, and here, being unable to make the turn, she went ashore, blocking also the channel to the two armed vessels. A heavy force of infantry with artillery now opened on the three, the gunboats replying for three hours, when the Warner hoisted a white flag. Lieutenant Lord of the Covington still kept up his fire and sent to burn the transport; but learning from the colonel in charge that there were nearly 125 killed and wounded on board he desisted. Soon after this the Signal was disabled. The Covington then rounded to and took the others in tow up stream, but her own rudders were disabled and the Signal went adrift. The latter then anchored, and the Covington running to the left bank tied up with her head up stream. In this position the action was continued with the enemy, reinforced now by the first battery which had been brought down, till the steam-drum was penetrated and a shot entering the boilers let out all the water; the ammunition gave out and several guns were disabled, one officer and several men being killed. Lord set the vessel on fire and escaped with the crew to the banks. On mustering, 9 officers and 23 men were found out of a crew of 76. Most of those who reached the banks escaped through the woods to Alexandria. The Covington was riddled, having received some fifty shots. The disabled Signal was fought with equal obstinacy by her commander, Lieutenant Morgan, but after the destruction of the Covington was surrendered, not burned; it being found impossible to remove the wounded under the fire of the enemy. The army marched out of Alexandria on the 14th toward Simmesport, which they reached on the 16th. Having no regular pontoon train, the Atchafalaya, which is here about six hundred yards wide, was crossed by a bridge of transport steamers moored side by side; an idea of Colonel Bailey's. The crossing was made on the 20th, and on that same day General Banks was relieved by General Canby, who had been ordered to command the Department of the West Mississippi, with headquarters at New Orleans. A.J. Smith's corps embarked and went up the river, and the expedition was over. The disastrous ending and the lateness of the season made it impracticable to carry out Grant's previous plan of moving on Mobile with force sufficient to insure its capture.