As previously discussed the term ''Floating Battery'' was mean to convey a man-made platform which could be floated in a Harbor, Lake or near a Coastline. Upon this platform was mounted a series of Artillery Pieces which were manned. The practice was to bombard positions on Land or to effect damage to unreachable locations of a Coastal or Harbor Fort. Prior to The American Civil war of 1861, the use of Floating Batteries were not seen. However, many in The Union (and later Confederate) Army High Command had served as Military Foreign Observers during the late Crimean War of The 1850s. French versions of Floating Batteries were very successful against Russian Coastal Forts and Positions.
With the Declaration of Secession in 1860, Southern States had begun to train and organize their State and Town Militia into an Army. Various Forts and Military Facilities were seized. Most Harbors and Ports in The South by 1861 had been controlled by Southern Forces – save that of Ft. Sumter in Charleston Harbor. The resolute Union Commander and his Garrison had refused multiple times ''requests'' to surrender. Sumter (which sat at the front of The Harbor was intended to be supported by a ring of smaller Forts ringing The Harbor. These were under Southern control. Although these Forts could (and did later) inflict much damage to Sumter, a more ''close in'' artillery barrage was needed.
At first, commandeered Ships (which constituted The Confederate Navy) – could be used, the overall firepower of Sumter would make short work of such attacks. This was when in 1861, several weeks before the actual attack on Ft. Sumter (and the official start of The War), Southern Engineers began working on what some saw as a ''joke'' – but others a ''marvel''.
Called The ''Floating Barn'' by Charleston citizens – The ''Floating Battery of Charleston Harbor'' never had an official name. Made of pine wood 12-inches thick (length beams), these were reinforced by the regional wood Palmetto (hard wood cut into 15-inch thick logs and laid crosswise). Reinforcing these, were ''Boiler Iron'' (iron treated to be used to handle the intense pressure of being made into Ship Boilers). The Battery was 100-feet in length and 25-feet in width. It supported (4) Artillery in the range of (2) 43-Pound Naval Guns and (2) 30-Pound Mortar.
Once The Battery was towed into a location roughly out of direct range of Ft. Sumter, it would be anchored to the Harbor sea bottom via (4) massive ship anchors. To further stabilize The Battery, over 500-pounds of sand placed inside of sandbags were placed in specially cut ''slots'' at the rear of The Battery Deck. This served as counter-balance.
The front of The Battery greatly resembled a large peaked Barn (hence it's nickname). Twin Decked, slots were cut into the facade thru which Cannon could be run out. In the case of Mortars, they fired up and over. The Battery had an attached Hospital which held (8) beds and space for (2) Operating Tables. Up to 24 men could live somewhat comfortably aboard The Battery.
Union Defenders of Ft. Sumter though little of The Battery until April 12, 1861, when now Confederate Forces opened fire on The Federal Garrison inside Sumter. The placement of The Floating Battery allowed them to score direct hits inside The Fort. They themselves were struck up to 6 times by Federal Guns, with little appreciable damage noted.
Even with Sumter's surrender some 36-hours later – and it's eventually being garrisoned by Rebel Forces until the end of The War, The Floating Battery still was deployed often again Federal Warships. However, by 1864 – with War material hard to come by, The Battery was stripped and gutted for just about all it's materials. With only a hulk found by Federal Forces in 1865, many Historians feel that much of The Floating Battery was used to build and or repair the few surviving Confederate Ironclad Warships still in service at the time. According to Battery ''Legend'', Northern Showman PT Barnum purchased a piece of The Battery Decking for display at his Museum in New York. It was lost in The Great Museum Fire of 1864.