Sailing ship tactics

Sailing ship tactics were the naval tactics employed by sailing ships in contrast to oared vessel tactics. This article focuses on the Age of Sail, a period from c. 1500 to the mid-19th century, after which sailing warships were replaced with steam-powered ironclads.

Since ancient times, war at sea had been fought much as on land: with melee weapons and bows and arrows, but on floating wooden platforms rather than battlefields. Though the introduction of guns was a significant change, it only slowly changed the dynamics of ship-to-ship combat. The first guns on ships were small wrought-iron pieces mounted on the open decks and in the fighting tops, often requiring only one or two men to handle them. They were designed to injure, kill or simply stun, shock and frighten the enemy prior to boarding. As guns were made more durable to withstand stronger gunpowder charges, they increased their potential to inflict critical damage to the vessel rather than just its crew. Since these guns were much heavier than the earlier anti-personnel weapons, they had to be placed lower in the ships, and fire from gunports, to avoid ships becoming unstable. In Northern Europe the technique of building ships with clinker planking made it difficult to cut ports in the hull; clinker-built (or clench-built) ships had much of their structural strength in the outer hull. The solution was the gradual adoption of carvel-built ships that relied on an internal skeleton structure to bear the weight of the ship. The development of propulsion during the 15th century from single-masted, square-rigged cogs to three-masted carracks with a mix of square and lateen sails made ships nimbler and easier to manoeuvre.

Gunports cut in the hull of ships had been introduced as early as 1501. According to tradition the inventor was a Breton shipwright called Descharges, but it is just as likely to have been a gradual adaptation of loading ports in the stern of merchant vessels that had already been in use for centuries. Initially, the gunports were used to mount heavy so-called stern chasers pointing aft, but soon gunports migrated to the sides of ships. This made possible for the first time in history coordinated volleys from all the guns on one side of a ship, broadsides, at least in theory. Guns in the 16th century were considered to be in fixed positions and were intended to be fired independently rather than in concerted volleys. It was not until the 1590s that the word "broadside" in English was commonly used to refer to gunfire from the side of a ship rather than the ship's side itself.

Naval tactics throughout the 16th century and well into the 17th century were focused on countering the oar-powered galleys that were armed with forward-facing heavy guns in the bow, which were aimed by turning the entire ship against its target. Though far less seaworthy than sailing vessels and highly vulnerable to boarding by ships that rode higher in the water, the galleys were a serious threat due to their ability to aim accurate heavy gunfire low in the hulls of larger sailing ships and to escape solely sail-powered opponents by rowing into the wind.

The line of battle tactic that allowed efficient use of broadside fire was not put into general use until the mid-17th century, as was described by English General at Sea Robert Blake in his Laws of War and Ordinances of the Sea. The previous solution was to make sailing ships fire backwards from the stern, as a defensive measure, or forward from the bow, as an offensive measure. The latter was only partially achieved either by canting (angling) the side guns towards the bow or stern as far as the ship's structure would allow, or by placing guns on the sterncastle and firing them in an arc on either side of the forecastle. Both solutions were problematic since they created a blind spot dead ahead and made it especially difficult to hit low-lying targets, like galleys. The method that was deemed most effective by contemporaries was to simply counter the threat of galleys with other galleys.

Despite the technical innovations, naval cannon fire also remained grossly inaccurate except at very close ranges. Difficulties in achieving standardization in metallurgy meant that all guns allowed for considerable "windage", meaning that bore diameters were about 10 percent larger than their ammunition. Combined with inefficient gunpowder and the difficulties inherent in firing accurately from moving platforms meant that naval tactics for sailing ships throughout the 16th century remained focused on boarding as a means of decisive victory.

Naval tactics in the Age of Sail were primarily determined by the sailing and fighting qualities of the sailing warships of the time. Three factors, in particular, constrained what a sailing admiral could order his fleet to do.

The 16th century saw the development of the man-of-war, a truly ocean-going warship, carrying square-rigged sails that permitted tacking into the wind, and heavily armed with cannons. The adoption of heavy guns necessitated their being mounted lower down than on top of the fore and after castles as previously where anti-personnel weapons had been positioned through the later Middle Ages, due to the possibility of capsizing. This meant that what had earlier been the hold of a ship that could be used either as a merchant ship or warship was now full with cannon and ammunition. Hence ships became specialised as warships, which would lead to a standing fleet instead of one based on placing temporary contracts.