Swivel Gun

Origins

The earliest shipboard guns of the fifteenth century were small wrought-iron pieces that could be handled without carriages, and mounting them on a pivoting yoke let them be fired over the rail rather than through gunports. By the time Portuguese caravels reached India, swivels — the Portuguese berço and the Spanish verso — were standard equipment, and the ships of da Gama, Columbus and the Conquistadors carried them in numbers. The breech-loading type, whose powder was carried in a separate removable chamber, so impressed Ming Chinese officials who met the Portuguese in the 1510s and 1520s that they copied it as the folangji, the 'Frankish gun', and produced it in thousands for their own ships and walls.

Design & Construction

A swivel is defined by its mount: a U-shaped iron yoke with trunnion holes, whose pin drops into a socket in the rail, the bulwark, the fighting top or the bow of a boat. A tiller — an iron bar or wooden handle at the breech — let the gunner traverse and elevate the piece by hand. Early breech-loaders, like the 'bases' recovered from Henry VIII's Mary Rose (sunk 1545), were forged from iron staves and hoops, with an open breech into which a pre-loaded chamber was wedged; spare chambers allowed a rapid succession of shots, though gas leaked at the joint. Later swivels were cast muzzle-loaders of iron or bronze, commonly firing a half-pound ball from a bore of roughly an inch and a half, and more often loaded with langrage, musket balls or nails. Effective range with case shot was short — tens of meters — which was exactly where it was needed.

Combat Use

The swivel was the gun of the boarding action. Mounted along the quarterdeck rails, in the tops, and on the bows of ships' boats, it swept an enemy's deck with shot as the vessels closed and broke up a boarding party climbing the side; defenders fired down into boats trying to board, and cutting-out parties carried swivels in their own launches. The merchant ships and privateers of the seventeenth and eighteenth centuries carried them as cheap insurance against boarding, and the pirate sloops of the Golden Age, small vessels with few carriage guns, mounted as many swivels as their rails would hold; the Golden Age Pirates preferred to terrify a prize into surrender, and a rail bristling with swivels and the Blunderbuss helped. Ashore, the same pieces served as wall guns on forts and trading posts from West Africa to the American frontier.

Legacy

The Royal Navy still listed half-pounder swivels in its establishments during the Napoleonic Wars, but the carronade and marines' musketry made them largely redundant by the early nineteenth century, and the machine gun later filled the same role. Swivel guns are regularly recovered from shipwrecks, and recovered bronze and iron examples, with their yokes, are among the most accessible pieces of real ship's ordnance for collectors; beside the heavy 32-Pounder Naval Long Gun below decks, they are the other half of the story of Naval Weapons in the age of sail.