A gunport is an opening in the side of the hull of a ship, above the waterline, which allows the muzzle of artillery pieces mounted on the gun deck to fire outside. The origin of this technology is not precisely known, but can be traced back to the late 15th century, with the appearance of artillery in naval warfare. Ships featuring gunports were said to be pierced, since the ports were cut through the hull after the construction.
History
Origin
The origin of the gunport is difficult to specify. In France, it has often been attributed to François Descharges (or Deschenges), a master carpenter in Brest in 1501; this is now known to be incorrect, since the ships of this era had long since adopted guns as their main armament. Examples of earlier occurrence are a 1498 terra cotta tile featuring a Portuguese caravel pierced with gunports; a relation of the Siege of Rhodes, printed in Ulm in 1496, that mentions a ship with 10 gunports; and a text that mentions that during the Conquest of the Canary Islands, Isabelle of Canary was thrown overboard through the gunport of Béthencourt's ship. Portuguese sources attribute the invention to King John II of Portugal (1455–1495), who decided to arm his caravels with heavy cannons, thus creating the first modern man-of-war. The first experiments with the new weapons were made in Setuvel (modern Setúbal) south of Lisbon around 1490; small ships armed in this way could confront much larger vessels armed with the usual small swivel guns. Guns had been mounted in ships since the 14th century. By 1386, naval artillery had progressed enough for Jean Froissart to report a large ship "armed with three guns that threw such large quarrels that wherever they fell, they pierced everything and caused great damage". In 1380, during the War of Chioggia, Luciano Doria was killed aboard his ship by an enemy broadside. In 1340, during the Battle of Sluys, several of the French carracks bore guns powerful enough to sink several English ships. But these guns were mounted in the ship's castles or in swivels, much in the way they were still mounted in the castles of the galleys at the Battle of Lepanto in 1571. The power of a cannon depends on its calibre and its range, which in turn impact its weight. The first artillery pieces used in naval combat, traced back to 1304, were light enough to be mounted on the forecastle, in line with the tactics of the time, which favoured attacks facing the bow the enemy. However, improvements in guns from the mid-14th century dictated an increase in weight, forcing ships to mount them low on the hull for stability; piercing gunports had therefore grown into a common practice by 1501. Some historians claim the invention was probably simultaneous in Portugal, Spain, England, France and Holland. It was made possible by the increased size of ship hulls, which allowed piercing ports high enough that they would not take in seawater; nevertheless, the ports had to close with lids in heavy seas, and making them watertight was a technical challenge at the time.
Age of Sail
Technique
The gunport makes it possible to mount large artillery pieces on a ship, turning it into an efficient artillery platform. From the 15th century, the number and quality of the artillery, conditioned by the gunports, became one of the features that distinguished warships from merchantmen. It announced the advent of the ship of the line and the demise of the galleys, which carried only a few guns on their forecastle. From the 16th century, the number and disposition of the artillery dictated the evolution of the silhouette of the ships, whose forecastle and quarterdeck faded and eventually disappeared entirely in the 19th century.
Gunports were pierced on the side of the hull at equal intervals of 2.4 to 2.7 metres, though some were also pierced at the bow and at the stern of ships, for chase guns. Their size was adapted to the calibre of the artillery: for instance a gunport for a 36-pounder long gun was 1.2 metre wide. On ships with several decks, they were never pierced one on top of the other, but in quincunx, as to better distribute the load of the guns and the weaknesses of the hull. They were not mere holes in the hull, but artillery positions that had to withstand the weight of the cannons and the recoil forces of shots; to this end, they featured strong beams and rings to which the complex rigging that held the guns in place were attached. In effect, naval guns mounted behind gunports were more comparable to the guns installed in latter turrets, than to mobile Army field guns. Georges Fournier describes that in 1643, gunports closed with a top-mounted lid mounted in France, England and Holland, while they closed with side-mounted doors in Spain, and with removable panels in other countries. Some ships built with clinker, such as the Mary Rose, had to be rebuilt with a freeboard to be pierced. Gunports also provided aeration to the cluttered ships. To this end, it was possible to either open the lid, like when bearing the guns, or to open a smaller door in the lid.
Flooding danger In heavy sea, the gunports of the lower battery had to be closed, lest sea water flood the gun deck. The lower ports were a recurrent flooding risk, and caused a number of shipwrecks, like the Mary Rose in 1545 and the Vasa in 1628 (these ships also suffered from poor stability due to excessive weight in their tops) which sank when sudden gusts of wind made them list and lowered their opened lower gunports under the level of the sea. During the Battle of Quiberon Bay, two French ships of the line, Thésée and Superbe, foundered for a similar reason. The loss of Vengeur du Peuple and the Third Battle of Ushant was also probably caused by seawater flooding from the lower battery, whose gunport lids had been ripped off and shattered in the collision and subsequent gunnery exchange with HMS Brunswick. The French term for "scuttling", "sabordage", comes from "sabord" ("gunport"), reflecting their potential for flooding.
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