Throughout this campaign the army and navy of the Union worked together as a single amphibious force. Grant's own words are no mere compliment, but the sober statement of a fact. "The navy, under Porter, was all it could be during the entire campaign. Without its assistance the campaign could not have been successfully made with twice the number of men engaged. It could not have been made at all, in the way it was, with any number of men, without such assistance. The most perfect harmony reigned between the two arms of the Service. There never was a request made, that I am aware of, either of the Flag-Officer or any of his subordinates, that was not promptly complied with." And what is true of Porter is at least as true of Farragut, who was the greater man and the senior of every one afloat. Grant could take Vicksburg only by reaching good ground, and the only good ground was below and in rear of the fortress. There was no foothold for his army on the east bank of the Mississippi anywhere between Memphis and Vicksburg. This meant that he must either start afresh from Memphis and try again to push overland by rail or cross the swampy peninsula in front of him and circle round his enemy. A retirement on Memphis, no matter how wise, would look like another great Union defeat and consequently lower a public morale which, depressed enough by Fredericksburg, was being kept down by the constant naval reverses that opened '63. Circling the front was therefore very much to be preferred from the political point of view. On the other hand, it was beset by many alarming difficulties; for it meant starting from the flooded Mississippi and working through the waterlogged lowlands, across the peninsula, till a foothold could be seized on the eastern bank below Vicksburg. Moreover, this circling attack, though feasible, might depress the morale of the troops by the way. Burnside's disastrous "Mud March" through the January sloughs of Virginia, made in the vain hope of outflanking Lee, had lowered the morale of the army almost as much as Fredericksburg itself had lowered the morale of the people.