Fort Taylor, the nation's southernmost Civil War era fortress, was part of the Third Tier System of Defense Fortifications plan. The fort is named for President Zachary Taylor, and construction began in 1845. In 1861, as Florida prepared to leave the Union, Federal artillery troops of Co. B, First U.S. Artillery secured Fort Taylor. The fort remained in Federal hands throughout the entire conflict. Its main role was to serve as headquarters of the U.S. Navy's East Gulf Coast Blockading Squadron. In 1898, Army engineers removed the top two tiers of the three-story fortress and constructed two Endicott-period coast artillery batteries over the Civil War-era casemates. The fort remained on active duty until 1947 when it was surplused to the U.S. Navy. Fort Taylor was named as a National Historic Landmark in 1973. The property was donated to the state of Florida in 1976 and opened to the public in 1985. The fort holds the largest cache of Civil War-era seacoast cannon in the U.S. Nearly 200 Rodman, Columbiad and Parrott cannon were used in the construction of Endicott batteries as in-fill. The cannon remain buried within the Endicott battery walls.