The siege of Port Hudson was conducted as a necessary adjunct to the more important siege of Vicksburg, about 130 miles to the north. The Confederate commander at Port Hudson, Major General Frank Gardner, had only about 7,000 men and was totally outnumbered by Nathaniel P. Banks' Union force of over 20,000. Consequently, the Confederates had little choice but to endure the privations of the siege, which were more severe— and less well known—than those at Vicksburg.
Port Hudson had first been fortified in August of 1862, when General John C. Breckinridge ordered heavy batteries to be built to control the river after his unsuccessful attempt to wrest control of Baton Rouge from the Union forces. Port Hudson is located on the east side of the Mississippi about twenty-five miles north of Baton Rouge. Its military significance stems from the fact that there are 80-foot high bluffs near the town that dominate a sharp bend of the river. Here some 20 heavy siege cannons were placed to blast any Union ships attempting to come upstream against the river's current.
On its landward side Port Hudson was protected by over three miles of works. These ran in a broad arc from Ross's Landing, a mile south of Port Hudson, to the mouth of Thompson's Creek, one-half mile north of the town. The defenses were built by slave labor and consisted of a ditch about 15 feet deep in front of a parapet about 20 feet thick. The line was augmented by four small forts—one at the southern apex of the line at Ross's Landing, one at the southeast corner of the works,