On the following day, the flag of the United States was floating over the city hall of New Orleans. General Butler and his troops took possession of the city on the first of May. On the 11th of July, on the recommendation of President Lincoln, Congress passed a resolution thanking Captain Farragut for what he had done; and a few days later he was further rewarded by being raised to the rank of rear-admiral. IX.--THE BATTLE OF MOBILE BAY. After the capture of New Orleans, Admiral Farragut was ordered at once to proceed up the river. He was to pass, or to attack and capture, all the Confederate forts between New Orleans and Memphis. But for many reasons, he thought it unwise to attempt this expedition. The increasing shallowness of the river would make it almost impossible to use his best sea-going vessels. The upper forts were located on high bluffs, and it would be difficult to attack them from the river. Admiral Farragut knew that, should he be able to pass these forts, or even to silence their guns, he could not hold them without a large land force. But he was too good a soldier to do anything in disobedience to orders. [Illustration: GENERAL N.P. BANKS.] In the face of all these difficulties, he passed and repassed the forts at Vicksburg and Port Hudson. He made it plain to the Confederates that none of their batteries on the Mississippi could stop the movements of his fleet. But he found, as he had expected, that the forts could not be held until armies came to his assistance. A large land force under General Grant besieged Vicksburg until it surrendered on July 4, 1863. Five days later, an army under General Nathaniel P. Banks succeeded in capturing Port Hudson. These were the last Confederate strongholds on the Mississippi. Their capture gave to the Union forces the entire control of the river. The command of the Mississippi squadron was given to David D. Porter, who had likewise been rewarded with the rank of rear admiral. He took charge of all the river boats of the fleet, while Farragut, with most of the sea-going vessels, sailed for the Atlantic coast. [Illustration: ADMIRAL DAVID D. PORTER.] These vessels were all in need of repairs. His flagship, the _Hartford_, which was in the best condition of all, had two hundred and forty scars from shot and shell. After the loss of New Orleans, Mobile was the best Gulf port left to the Confederates. This city stands at the head of the broad, shallow bay of Mobile, thirty miles from the Gulf. The entrance to the bay is very narrow, and it was protected by two strong forts,--Fort Morgan on one side, and Fort Gaines on the other. Admiral Farragut was ordered to capture these forts. This would prevent the South from using the port of Mobile. On January 18th, 1864, his ships having been repaired, Captain Farragut sailed again into the Gulf of Mexico. He was anxious to make the attack early in the spring, but it was August before his fleet was ready.