After crossing the Mississippi River and fighting the battle of Port Gibson April 30 - May 1, 1863, Gen. U.S. Grant moved to capture Grand Gulf as a base of operations against Port Hudson, Louisiana. After capturing Grand Gulf on May 3, Grant learned that Union forces under Gen. Nathaniel P. Banks were not yet in position at Port Hudson and decided to move against Vicksburg instead. Grand Gulf then became Grant's forward supply base, and by May 8 over 2,000,000 rations were stockpiled there for Grant's army.