With Ulysses Grant’s Federals at the gates of Vicksburg, on May 21, 1863 Union forces under General Nathaniel Banks moved out of Baton Rouge and Alexandria, Louisiana and headed toward Confederate held Port Hudson on the Mississippi River.
Except for Vicksburg, Port Hudson was the remaining Confederate defense on the Mississippi River. Like Vicksburg, it had to be held at all costs to prevent the Confederacy from being bisected at the Mississippi River.
Banks’ forces engaged the Confederates in a minor action on the west side of the Mississippi at Plains Store near Bayou Sara. Although not apparent at the time, Banks’ movements would subsequently result in an approximate fifty day siege of Port Hudson. After Vicksburg’s surrender in July to Ulysses Grant, Port Hudson would also capitulate to the Federals.