In the meanwhile Grant had moved on the western side of the Mississippi, from Milliken's Bend to a point opposite Grand Gulf. There he found the Confederates strongly fortified, but by moving down the river to Bruinsburg he succeeded in getting his army across on the thirtieth of April. If the reader will now look at a map, remembering that Vicksburg and Port Hudson were both held by the Confederates, and that the regions along the river bank on the western side of the stream were quagmires, traversed at every step by impassable streams and bayous, he will have some conception of the boldness of this movement of Grant's. The great fighter had deliberately carried his army into a position where he had no possibility of communication with any base of supplies in either direction. He had cut himself off from all help and must henceforth rely exclusively upon himself. He had put himself in a position where victory was the only alternative to destruction. During all the course of the war no other general on either side ventured upon so desperate a risk as this. Having marched over difficult roads, and by circuitous routes, Grant had brought with him, of course, supplies of food and ammunition sufficient only for a very brief campaign. For further food than this he must depend upon a country by no means rich in supplies at any time, which had already been stripped nearly bare by the requisitions of his adversary. For ammunition, beyond the store that he had in his caissons and cartridge boxes, he had no supply-source at all. To employ the old metaphor of war history, he had completely burned his ships and his bridges behind him. But at least and at last he had succeeded in placing himself in a position from which he could operate in the rear of Vicksburg. The Confederate general, Joseph E. Johnston--just recovered from the well-nigh mortal wound he had received at Seven Pines--had been sent to Jackson, Mississippi, less than fifty miles east of Vicksburg to take command of such forces as could be gathered there. He had in fact collected a considerable body of men whose numbers Grant could in no wise ascertain. Nevertheless, Grant determined to push his own army into a perilous position between that of Johnston at Jackson, and that of Pemberton near Vicksburg. He was aided in this by a great cavalry raid which had recently been made by Grierson from the north which swept through the Mississippi country, desolating it and occupying the attention of the Confederates in many quarters from which, but for this diversion, Johnston might easily have drawn reinforcements.