Floating battery

A floating battery is a kind of armed watercraft, often improvised or experimental, which carries heavy armament but has few other qualities as a warship.

During the capture of Mahdia in 1550, Spanish captain Garcia de Toledo Osorio built a floating battery to bombard the city. The fortified, nine-gun battery was built over two galleys and became decisive to take the position. It was designed by Sicilian engineer Andronico de Espinosa and built over galleys owned by Toledo and admiral Andrea Doria.

Use of timber rafts loaded with cannon by Danish defenders of Copenhagen against bomb ketches of a combined British-Dutch-Swedish fleet is attested by Nathaniel Uring in 1700.

In 1727, Spanish engineer Juan de Ochoa proposed King Philip V his project of the barcaza-espín ("barge-porcupine"), heavily armored floating batteries moved by rows and fitted with multiple rams. The end of the Anglo-Spanish War, however, buried the project before it could be implemented.

An early appearance was in 1782 at the Great Siege of Gibraltar, and its invention and usage is attributed to French engineer Jean Le Michaud d'Arçon.

A purpose-built floating battery was Flådebatteri No. 1, designed by Chief Engineer Henrik Gerner in 1787; it was 47 m (154 ft) long, 13 m (43 ft) wide and armed with 24 guns, and was used during the 1801 Battle of Copenhagen under the command of Peter Willemoes. The British made limited use of floating batteries during the French Revolutionary and Napoleonic Wars, with the two-vessel Musquito and Firm-class floating batteries, and some individual vessels such as HMS Redoubt.

The most notable floating batteries were built or designed in the 19th century, and are related to the development of the first steam warship and the ironclad warship.

Demologos, the first steam-propelled warship, was a floating battery designed for the protection of New York Harbor in the War of 1812.