to the main river for water transportation. When railroads provided more convenient commerce, however, levees to contain the flow had been built, and the land was partially drained. Then, when the war came, the levee was breached for the Yazoo Pass expedition, and the land was again flooded. Minor waterways swelled to the size of small rivers, raising the possibility that Union gunboats could travel on them. Porter believed that he could send his gunboats and army transports up Steele's Bayou (present-day Steele Bayou) to Black Bayou, into Deer Creek, then Rolling Fork, and finally into the (Big) Sunflower River. The last met the Yazoo River a short distance upstream from the bluffs where a major Union attack had been repulsed in late 1862. Porter had to rely on imperfect maps and the advice of local citizens who did not understand the difficulties of moving heavy warships in a narrow channel with numerous bends. He was therefore unprepared for the problems presented by Deer Creek. There the straight-line distance between the entry point at Black Bayou and the exit at Rolling Fork, , was only half the distance along the creek, . He was also unaware of the impedance to mobility imposed by the overhanging trees that grew down to the water's edge and by the submerged vegetation that seized the hulls of his vessels. When encountered, these problems limited progress of the gunboats to as little as every two hours. Start of the expedition and Confederate response The expedition entered Steele's Bayou on March 14. The naval contingent was spearheaded by five Pook turtles, , , , , and . Four tugs pulling mortar rafts added to the firepower. In addition, soldiers in two Army transports followed the flotilla. General Sherman himself was with the troops. The gunboats got through Steele's Bayou and Black Bayou by the end of the second day, and there Sherman overtook them. He saw that the overgrowth would be a serious obstacle; while the armored gunboats could push aside the limbs in their path, the smokestacks and upper works of the flimsier transports would be severely battered. Nevertheless, Porter decided to push on, and Sherman returned to bring up the rest of his soldiers. Meanwhile, the Confederate Army was not idle. Major General Carter L. Stevenson, who commanded the Confederate district, was aware of the growing threat to Vicksburg almost as soon as the