Union Admiral David Dixon Porter leads 12 ships past the heavy barrage of Confederate artillery at Vicksburg, Mississippi. He lost only one ship, and the operation speeded General Ulysses S. Grant's movement against Vicksburg.
Grant had been trying to capture Vicksburg for six months. A first attempt failed when General William T. Sherman's troops were unsuccessful in attacking Vicksburg from the north. Grant now planned to move his army down the opposite bank of the river, cross back to Mississippi, and approach the city from the east. The soggy spring conditions slowed his advance to a crawl as his force had to build bridges over the bayous on the Louisiana side of the river. To speed the operation, Grant called on Porter to take the ships loaded with men and supplies and run past the powerful Vicksburg batteries.
The flotilla quietly moved down the river on the dark night of April 16. The exhausts on the steamboats were vented into the paddle wheel housing to muffle the noise. The boats were positioned off center so that if a ship were hit, the following craft could pass safely. The ships were stacked with cotton bales to act as a soft armor in the event of a direct hit. Confederate pickets spotted the flotilla and sent word to the batteries, and the bombardment began. The commanding Confederate, General John Pemberton, was attending a ball and was quickly summoned to the scene. Some Rebel soldiers even rowed across the Mississippi River to set fire to the trees on the western bank and provide backlighting for their gunners on the eastern shore.
It took over two hours for the ships and attached barges to pass. The Union lost only one ship and two barges, and Grant's plan proceeded. Within six weeks, he had locked up Vicksburg from the east and the siege began. Vicksburg would surrender on July 4, 1863.