Fort Jackson, Historic masonry fort in Triumph, United States

Fort Jackson is a military fortification on the western bank of the Mississippi River in Plaquemines Parish, Louisiana, built from thick brick walls in the shape of a five-pointed star. The ramparts extend over several hectares and enclose a central parade ground, from which passageways lead to gun emplacements and underground storage rooms.

Construction of the fortification began in 1822 as part of a defense system to protect New Orleans and was completed in 1832 after US military engineers revised colonial-era plans. In April 1862, Union forces bombarded the installation during a multi-day battle that ended with Confederate surrender and opened the Mississippi River to northern forces.

Named after Andrew Jackson, the structure houses exhibits of weapons, uniforms, and documents from several wars, giving visitors direct insight into military life along the Mississippi. Inside the old casemates, original cannons remain pointed toward the river, making the strategic role of the post tangible.

The installation lies about 65 miles (105 kilometers) south of New Orleans along Louisiana Highway 23 and is accessible via a well-marked access road. The grounds offer parking in front of the museum, and visitors can explore the ramparts and casemates on their own or sign up for a guided tour.

French champagne producer Charles Heidsieck spent seven months at the installation after Confederate soldiers arrested him on suspicion of espionage. His detention in 1862 ended only when French diplomats intervened and secured his release.