Probably few generals have ever encountered a situation more difficult, or one in which military precedents helped so little. The fortress occupied a height commanding on the north and west, along the river, swampy bottom-lands, at the moment largely submerged or threaded with channels. These lowlands were much overgrown with canebrake and forest; roads there were almost none, the plantations established within the area being approached most conveniently by boats. But it was from the north and west, apparently, that Vicksburg must be assailed, for the region south of the city appeared quite beyond reach, since the batteries closed the river, which seemed the sole means of approach for Northern forces. The surest approach to the stronghold was from the east; but there Grant had tried and failed; public sentiment would not sustain another movement from that side. There was nothing for it but to try by the north and west, and Grant grappled with the problem. Besides the natural obstacles, he had to take account of his own forces, and the strength and character of his adversary. In November, 1862, Johnston, not yet recovered from the wounds received at Fair Oaks in May, was ordered to assume command in the West, taking the troops of Kirby Smith, Bragg, and the army defending the Mississippi. The latter force, up to that time under Van Dorn, was transferred to John C. Pemberton, of an old Pennsylvania family, before and after the war a citizen of Philadelphia. Though a Northerner, he had the entire confidence of both Jefferson Davis and Robert E. Lee. His record in the old army was good; he was made lieutenant-general by the Confederacy, and received most weighty responsibilities. He served bravely and faithfully the cause he had espoused; though outclassed in his campaign, he did not lack ability. Pemberton commanded some fifty thousand men, comprising not only the garrison of Vicksburg, but also that of Port Hudson and detachments posted in northern Mississippi. On the watch at such a point as Jackson, the state capital, he could, on short notice, concentrate his scattered command to meet whatever danger might threaten. Against this alert adversary Grant could now oppose about an equal number of men, comprised in four corps--the Thirteenth (McClernand), Fifteenth (Sherman), Sixteenth (Hurlbut), Seventeenth (McPherson). Hurlbut was of necessity retained at and near Memphis, to preserve communications and hold western Tennessee; the three other corps could take the field with about forty-three thousand. Among Grant’s lieutenants, two were soldiers of the best quality--Sherman and James B. McPherson, the latter a young officer of engineers, who during the preceding months had been coming rapidly to the front.[232] Besides the army, Grant had a powerful auxiliary in the fleet, which now numbered seventy craft, large and small, manned by fifty-five hundred sailors and commanded by David D. Porter, an indefatigable chief.