The correct answer is the Battle of Port Hudson (also known as the Siege of Port Hudson.)
This battle took place from March of 1863 until July of 1863. This battle between the Union and Confederacy fighting over a strategic location along the Mississippi River. The goal of the Union army was to take over Port Hudson from Confederate control. Continuing to take over different ports along the Mississippi River would give the Union a significant advantage, as it would limit the amount of supplies the Confederates could send to each other.