by late summer of 1862, only Vicksburg and Port Hudson appeared to be major constraints to the Union. Of the two posts, Vicksburg was by far the strongest and most important. Setting high over looking a bend in the river, protected by artillery and dangerous swamps. So far the city had defied Union efforts to force it into submission. In order to protect the Mississippi Valley, Confederates established a line of defense, which ran from Columbus, Kentucky, overlooking the Mississippi River trough Bowling Green to Cumberland Gap where the bright flank was secure on the mountains. On the Mississippi River, south of Columbus, fortifications were also placed on island number 10 and on the Chickasaw Bluffs north of Memphis. Seventy miles below New Orleans, two powerful masonry forts supported Jackson and St. Philip stood guard at the mouth of the Mississippi River. Anxious to confront the task, Union land and navel forces moved from two directions. In a huge attack to gain control of the Mississippi from the Confederate troops heading south from Cairo, Illinois, federal forces took forts Henry and Donelson on the Tennessee and Cumberland Rivers respectfully and opened the pathway of invasion to the south. Efforts by Union land and navel forces to capture Vicksburg and open the great waterway to navigation ended in failure. It was only a matter of time before war centered in on Vicksburg. The first threat developed in May 1862, when the ships from the West Gulf Blockading Squadron arrived bellow Vicksburg and demanded that they surrender. The surrender was refused. It was then realized by both Union and Confederate high commands that if Vicksburg were going to fall, it would be in the hands of a huge combined land and navel effort. A decision was made to construct a line of defense around the city, which would guard the road and railroad access to Vicksburg. Strategists in Washington had no choice but to use...
