Union forces built Fort Butler on this site in late 1862 because of the strategic importance of the river port at the mouth of Bayou Lafourche. The earthen, log, and brick fort no longer exists. On the evening of June 27, 1863, Confederate forces advanced on the fort hoping to capture it in a daring assault that would overwhelm its small garrison, but when they reached the riverbank they encountered a moat and palisade that hampered the attack and it quickly fell apart. Gunfire from the fort and Union gunboats on the river proved deadly, and the Confederates retreated, leaving scores of dead and prisoners behind. Infantry from the 28th Maine Volunteer Regiment, along with a number of former slaves and convalescent soldiers in the fort, fired on the attacking Confederates below, while artillery fire from the Union gunboats took a toll on men from Texas and Arizona. Union casualties were light. Archaeological excavations in the late 1990's revealed the fort's structural details and a variety of artifacts, including many brickbats said to have been hurled when soldiers' gunpowder got wet and their guns failed to fire.