Boarding, in its simplest sense, refers to the insertion onto a ship's deck of people. However, when it is classified as an attack, in most contexts, it refers to the insertion of personnel that are not members of the crew by another party. Boarding may be carried out during wartime by naval infantry in an attempt to seize and possibly destroy the vessel, or it may occur in peacetime by pirates and other criminals, or as a means of inspection by a nation's coast guard (or navy) to prevent piracy and smuggling.
In modern warfare, boarding by military forces may involve the use of small submersibles, inflatable boats, or helicopters to carry troops to the deck of the ship, or may simply be carried out by scuba divers scaling the sides of the ship.
Boarding is one of the oldest methods of securing an opposing ship, as the first cases were depicted when the Sea Peoples and Egyptians fought. For cultures that lack effective shipboard artillery, boarding is the main technique of ship-to-ship combat. However, in the modern era, boarding is still used, particularly when stealth is desired.
In all eras, boarding requires that the ship boarded be stable enough to withstand the impact of enemy personnel leaping or climbing onto the deck and a subsequent sustained fight. The target ship must also have enough deck space for boarders to be able to stand and fight effectively. Thus, Native American war canoes or New Zealand longboats were not suitable boarding targets, and wars between sides equipped with such vessels have generally not seen boarding actions, or any other decisive form of ship-to-ship combat. Instead, such vessels were often used for the rapid transportation of troops and supplies, and decisive engagements were normally fought by landing forces.
Throughout the classical and medieval periods, all naval ship-to-ship combat focused primarily on boarding, although ramming and incendiaries were secondary tactics. Greek and Persian naval tactics emphasized ramming and boarding, notably at the Battle of Salamis.
The earliest Roman naval battles against Carthage also emphasized boarding. Since the Romans were primarily a land-based army, they could not effectively combat the Carthaginian navy, and subsequently lost several sea battles. The corvus, a boarding ramp with two steel spikes, was the Roman answer to this problem. Roman sailors piloted their ship alongside a Carthaginian ship, dropped the corvus from one deck to the other, and sent their soldiers across the board, assaulting the ship. The Carthaginian navy, unprepared for this "land combat" on the oceans, lost several ships to this tactic. This invention secured Roman naval dominance in the Mediterranean Sea for several centuries.
During the medieval period, boarding continued to be the dominant form of ship-to-ship combat. The most prominent naval power of the period, the Vikings, rarely fought other seaborne peoples on the water, but they still depended on boarding on those rare occasions, often lashing their longships together to make a more stable platform for the upcoming battle. The maritime use of Greek fire made Byzantium less dependent on boarding than other medieval powers, but it was still used.
In medieval Western Europe, boarding actions were relatively rare, as general dependence on oarless sailing vessels unable to steer close to the wind tended to keep at least one side's fleet imprisoned in port while the other fleet ferried soldiers to its objective. The most famous exception to this rule was the Battle of Sluys in 1340, where the French and English navies fought each other with close combat weapons, bows and primitive firearms, using the ships' decks and compartments as battlefields. Contemporaries noted at the Battle of Sluys that ship-to-ship boarding actions were particularly deadly, due to the fact that retreat was impossible, (short of jumping off the ship and drowning) so the losing side thus must "bear the fortune." This meant that these boarding actions were almost always fought to the death.
To better resist boarding, medieval European ships began to be built with high wooden "castles" fore and aft, which boarders could scale only with great difficulty, while archers or harquebusiers could sweep the enemy decks.
Medieval China and Japan were also dependent on boarding tactics, with the flat expanse of a ship used as a battleground for the marine contingents on the ships. The Battle of Dan-no-ura in 1185 was one of the classic naval battles in medieval Asia to be decided by boarding.
The development in the early 16th century of shipboard gunports and gun carriages, and the consequent adoption of broadside tactics, gradually ended the primacy of boarding in naval warfare.
The decline in boarding occurred faster in Northern and Western Europe than in the Mediterranean. While England and France quickly designed ships with heavy broadsides, the Mediterranean's lighter winds encouraged the Spaniards, Italians and Turks to retain the rowed galley, which was difficult to equip with heavy broadsides because the weight and size of the artillery interfered with the oar banks. As late as 1571, the Mediterranean Battle of Lepanto, while influenced by artillery, was still principally a battle determined by boarding, with soldiers aboard the ships on both sides outnumbering the sailors by over two to one.
The defeat of Spain's Great Armada in 1588 struck the death knell for major fleets geared toward boarding. The Spanish galleons were intended primarily for boarding combat, their garrisons of boarding soldiers far outnumbering the English and their decks provided with high castles for suppressive fire. But the Armada proved unable to close with the English vessels, partly because the Spanish castles rendered their ships more sluggish, while Drake and Hawkins stood off and bombarded the Spanish from long range, tearing up their rigging and decimating their crews with the superior firepower of their broadsides. This enabled the outnumbered English fleet to avoid being boarded and prevent a Spanish landing.
While boarding would never again be the dominant tactic in Western naval warfare, it was not abandoned. Boarding was still used as the coup de grace against a crippled ship, enabling the victimized vessel to be recovered and used by the boarders' side rather than being sunk. Important information such as enemy plans, ciphers or rutters might also be recovered. Large quantities of soldiers were consigned to transports rather than "pestering" the decks of warships, but smaller units of specialized marines were kept aboard to aid in boarding (as well as to enforce naval discipline). Sailors themselves were now expected to play the major role in boarding combat.
Boarding was of particular importance in the 17th and 18th centuries' guerre du course, or commerce raiding, as well as to privateers and pirates. Because naval crews were paid prize money for bringing back enemy merchant shipping and cargoes intact, it was preferable to capture such ships rather than sink them, which ultimately required boarding, with or without a preliminary artillery duel. Privateers and pirates found boarding even more necessary, as both depended entirely on capturing merchant vessels for their livelihood, under the wageless system of "no purchase, no pay".
There were two chief techniques of boarding in the Age of Sail. One was to bring the two ships close enough to actually step from or leap from one's own gunwale to the enemy's deck. Grappling hooks and lines assisted in keeping the vessels side by side. The second option was to place a boarding party onto a dory, gig, or another type of small boat, row it alongside the target, and then climb aboard by using grappling hooks or the steps built into some ship's sides. The cinematic method of throwing a grappling line into the enemy's rigging or yards and then swinging aboard does not appear to have any historical support, as this could hardly have been practical, and brought a soldier within range of a large group of hostile combatants extremely quickly. In addition, it would be hard for large numbers sufficient to overwhelm the other ship's defenses to be brought onto the deck in this fashion.
Boarding in the Age of Sail was more difficult and dangerous than in previous eras of open-decked sailing vessels. Defenders could seek cover in "closed quarters" in the ship's roundhouse or foredeck, shooting through small loopholes at the exposed boarders. The defenders could also place grenades on their gunwales or dangle them from their yards, detonating them by fuses of quick match that led back through the loopholes into the closed quarters. If not in closed quarters, defenders sometimes resorted to the boarding pike, trying to kill or wound boarders while keeping them at a distance, and of course might use any of the weapons that the boarders themselves used.
Boarding weapons in the Age of Sail consisted of grenades, muskets, pistols, cutlasses, numerous other blades, and the short-barreled shotguns called blunderbusses. Until the 19th century introduction of the percussion cap, sailors preferred to use flintlocks whenever possible, as the lighted match of a matchlock was extremely dangerous to use on board a ship. Spanish and Portuguese sailors, especially officers, were known to use the rapier throughout the 17th and even into the 18th century, but the close-quarter nature of boarding combat rendered these lengthy swords very ineffective. An important weapon often overlooked by historians was the boarding axe, useful for attacking the enemy, but also essential for chopping down doors and bulkheads to break into closed quarters where the defenders of a ship could barricade themselves.
The continued success throughout the 18th century of boarding tactics in a secondary role is best exemplified by John Paul Jones' assault against the HMS Serapis from the sinking USS Bonhomme Richard in 1779, the only known case in the Age of Sail where a ship's captain captured an enemy ship while losing his own. The HMS Shannon in turn broke the United States' run of successful frigate battles during the War of 1812 by boarding and capturing the USS Chesapeake in 1813.
The "cutting out expedition," a boarding attack by small boats, preferably at night and against an unsuspecting and anchored target, became popular throughout the later 18th century and during the Napoleonic wars. This heralded the emphasis on stealth and surprise that would come to dominate future boarding tactics.
The adoption of ironclads and increasingly powerful naval artillery vastly increased the risk of boarding attacks. Meanwhile, the suppression of piracy and the abandonment of privateering and prize money made boarding actions even against merchant vessels less rewarding. The massacre of Paraguayan canoe-borne boarding parties by Brazilian ironclads during the Paraguayan War demonstrated the futility of direct assault by boarding in the face of 19th-century technology.
For the most part, boarding became a police action in which the attackers came on board only when no resistance could be expected, in order to search vessels and remove contraband. The target would be a ship that had hove to or surrendered. During wartime, the surrendering or sinking ship would be searched for any valuable information such as plans and ciphers. One prominent example would be during World War II, when a British vessels crippled the U-110 in 1941, and sent its crew onboard after the U-boat commander, Kapitänleutnant Fritz-Julius Lemp, gave the order to abandon ship. The British would be rewarded with a fully operational Enigma cipher machine, left behind by the German sailors.
True boarding assaults in the 19th, 20th, and 21st centuries became extremely rare, generally by small boats or by divers, who entered the target vessel surreptitiously and exploited total surprise to seize control before resistance could be effectively organized. Modern-day pirates in motorboats similarly depend on speed, stealth and surprise to take their targets, usually unarmed and poorly defended, without serious resistance.
Besides video games, boarding is prominently featured in some films based in the age of the sail, for instance, in the Pirates of the Caribbean franchise, as well as those set in the future.
In science fiction works dealing with starships, boarding actions are often made easier by the use of fictional advanced technology, most notably tractor beams to immobilize and "reel in" a target vessel, and transporters to teleport, or "beam", directly from one ship to another. In these works, it is often necessary to first cripple or disable the target ship in some way, such as taking down its shields, or disabling its faster-than-light drive so it can't escape, before boarding it.
In settings with teleportation technology (which allows boarders to instantly transition between their own ship and any arbitrary location aboard the ship being boarded), such as the transporters of the Star Trek franchise, such technology is often the preferred method of boarding another vessel, as it is faster than any other method and, in most cases, allows boarders to be inserted directly into key locations, such as the bridge or engine room, on the ship to be boarded. Generally, such technology only works if the shields of the defending ship are down (and requires the attacking ship to briefly drop its own shields), but deflector shields are generally also capable of blocking solid objects such as space-suited marines, boarding craft or docking tubes. Transporter technology is sometimes also used for hit-and-run boarding actions, in which a boarding party beams directly to the site of their objective (or in an oft-used plot device, into an area "as close as possible" to that objective, either due to limitations of the teleportation technology ("the chamber itself is shielded") or so as not to attract (as much) attention), carriess out a specific task (such as sabotage, data theft or grabbing or sticking transport beacons on people or objects) and beams out as quickly as possible, rather than trying to seize control of the ship.
Boarding was featured in the Star Wars universe, both in the films and video games (such as X-Wing vs. Tie Fighter). A ship would often be boarded after being disabled with ion cannons, either by another large ship, or by a transport craft. In the case of a small vessel being captured by a larger one (typically a capital ship), the latter vessel may use a tractor beam to immobilize and "reel in" the target vessel.
In some space RTS games, boarding is performed by special ships (usually called "troopships", "marine transports" or something similar), which dock with a ship to be boarded and, depending on the game, either instantly capture the target ship (usually consuming the troopship), or start a boarding action requiring a finite amount of time (bigger ships usually take longer to capture, but it is usually possible to hasten a boarding action by using additional troopships), after which the target ship is automatically captured; in the latter case, a ship being boarded can be saved from capture by destroying the offending troopships before they finish their task; depending on the game, it may be necessary to disable a ship before boarding it, and not all ship types (fighters, for example) may be boardable.