The line of bluffs which marks the eastern boundary of the Mississippi Valley leaves the river at Memphis, curves in a great 250-mile arc away from the river, and then swings back to reach the river again at Vicksburg. Enclosed between the bluffs and the river is the “Delta”—a strip of land averaging some 60 miles in width, which is now a fertile, well-drained, cotton-growing region. In 1863, it was a swampy bottom land containing numerous rivers and bayous, subject to incessant floods. It was covered with thick forests and dense undergrowth, a condition, which, according to Grant’s engineer officer, “renders the country almost impassable in summer, and entirely so, except by boats, in winter.” This impenetrable swampland, lying before the bluffs, effectively guarded Vicksburg’s right flank. Unless the waterways of the Delta might provide a passage to the bluffs, operations against Vicksburg to the north were hopeless. [Illustration: _Maj. Gen. U. S. Grant, commanding the Union Army of the Tennessee._ Courtesy National Archives.] [Illustration: _Lt. Gen. John C. Pemberton, commanding the Confederate Army of Vicksburg._ Courtesy Flohr Studio, Vicksburg.] South of Vicksburg the prospect for the Union Army was equally dismal. After meeting the river at Vicksburg, the bluffs follow the river course closely to the south and were accessible, therefore, to troops from the Mississippi River. But the river batteries of the city prevented passage of transports to the river below; for troops to get below the city it was necessary to move through the Louisiana lowlands west of the river. This region was like the Delta north of Vicksburg—flooded bottom lands interspersed with bayous, rivers, and lakes. It would prove equally obstinate to land movements. To increase Grant’s difficulties, his campaign against Vicksburg was begun during the wet season when streams were overflowing and lowlands impassable. The winter of 1862-63 was a period of unusually high water, the Mississippi cresting higher than its natural banks from December until April. Had Grant reached Vicksburg during the dry season, his problem would have been less formidable. Until the bottoms were dry enough to permit land movements, the Union commander felt himself compelled to keep the army active. Even if success along the water routes seemed unlikely, he reasoned that prolonged idleness would be injurious to the health and morale of his troops. Grant had come to believe that military success was won by the aggressive. To Grant’s critics, who demanded that he open the Mississippi without delay or be replaced by someone who could, Lincoln replied, “I can’t spare this man; he fights.”