Chattahoochee, Florida This historic site, the original officers’ quarters of the Apalachicola Arsenal are listed on the National Register of Historic places. Built in 1834-1839, the historic Apalachicola Arsenal stood on the grounds of what is now the Florida State Hospital in Chattahoochee. It was the scene of the first military encounter of the Civil War in Florida. When Florida became a U.S. territory in 1821, its defense emerged as a key consideration for the federal government. Forts were built along the coastline and a site on the high hills overlooking the confluence of the Flint and Chattahoochee Rivers was selected for the building of a permanent arsenal. The two rivers unite to form Florida’s Apalachicola. Construction of the arsenal began in the spring of 1834 and continued until the impressive walled complex was completed in 1839. The Apalachicola Arsenal served as a supply depot during the Second Seminole War (1835-1842). Its workshops made cartridges, gun carriages and repaired weapons during that conflict. Local residents used its 9-foot high, 30-inch thick walls for protection on several occasions when bands of resisting Creek warriors carried out attacks in the area. Important gunpowder experiments were carried out at the facility during the 1850s by the U.S. Army.