When he arrived there on January 30th, he was faced with a hard problem. Vicksburg was built on a bluff running roughly along the Mississippi River. Repulsed at Chickasaw Bayou, Sherman had shown the difficulty of attacking the bluffs themselves, and Grant had already retreated from an attempt to march overland because of strikes at his supply lines, and the batteries at Vicksburg were so strong it was clear the navy would not attempt to silence the guns. That left Grant with two options. He could try to run the batteries, a dangerous proposition in unarmored transports, or he could try to find a way to go around, which is what he set out to do.