Three days after Farragut passed the batteries of Vicksburg, on the 1st of July, the Mississippi flotilla, under the command of Flag-officer Charles H. Davis, joined him from above; having left Memphis only two days before, but favored in their voyage by the current, by competent pilots, and by a draught suited to the difficulties of river navigation. The united squadrons continued together until the 15th of July, lying at anchor near the neck of the promontory opposite Vicksburg; with the exception of the Brooklyn and the two gunboats which had not passed up on the 28th of June. These remained below the works, and on the opposite side of the promontory. The position of the two flag-officers was about four miles below the mouth of the Yazoo River, a tributary of the Mississippi, which enters the main stream on the east side not far above Vicksburg. It was known to them that there was somewhere in the Yazoo an ironclad ram called the Arkansas; which, more fortunate than the Mississippi at New Orleans, had been hurried away from Memphis just before that city fell into the hands of the United States forces. She was a vessel of between eight hundred and a thousand tons burden, carrying ten guns, which were protected by three inches of railroad iron, backed by bales of compressed cotton firmly braced. Her most dangerous weapon, however, was her ram; but, owing to the lightness and bad construction of the engines, this was not as formidable as it otherwise might have been to the enemy's ships. So little injury had thus far been done to the United States vessels by the rams of the Confederates that the two flag-officers were probably lulled into a state of over-security, and they allowed their squadrons to lie with too low fires. To this doubtless contributed the more powerful motive of the difficulty to the coal supply incurred by the excessively long line of exposed communications, imposed upon both squadrons by the stubborn persistence of the Navy Department in hurrying the fleets far in advance of any support by the army. Beyond the reach of their guns they could not control the river banks; and, unless they could be present everywhere along the eight hundred miles which separated Memphis from New Orleans, even the narrow strip on either side swept by their cannon was safe at any point only while they were abreast it. The moral effect of their promenade up and down and of their meeting at Vicksburg was accurately weighed by the enemy; and, however it may have imposed upon the Northern people, did nothing to insure the safety of the unarmed vessels upon which supplies depended. This essentially vicious military situation resulted necessarily in a degree of insecurity which could have but one issue--a retreat by both squadrons toward their respective bases, which soon after followed.