A navy or maritime force is a fleet of waterborne military vessels (watercraft) and its associated naval aviation, both sea-based and land-based. It is the branch of a nation’s armed forces principally designated for naval and amphibious warfare; namely, lake-borne, riverine, littoral, or ocean-borne combat operations and related functions. It includes anything conducted by surface ships, amphibious ships, submarines, and seaborne aviation, as well as ancillary support, communications, training, and other fields. The strategic offensive role of a navy is projection of force into areas beyond a country’s shores (for example, to protect sea-lanes, ferry troops, or attack other navies, ports, or shore installations). The strategic defensive purpose of a navy is to frustrate seaborne projection-of-force by enemies. The strategic task of the navy also may incorporate nuclear deterrence by use of submarine-launched ballistic missiles. Naval operations can be broadly divided between riverine and littoral applications (brown-water navy), open-ocean applications (blue-water navy), and something in between (green-water navy), although these distinctions are more about strategic scope than tactical or operational division.
In most nations, the term “naval”, as opposed to “navy”, is interpreted as encompassing all maritime military forces, e.g., navy, naval infantry/marine corps, and coast guard forces.
First attested in English in the early 14th century, the word “navy” came via Old French navie, “fleet of ships”, from the Latin navigium, “a vessel, a ship, bark, boat”, from navis, “ship”. The word “naval” came from Latin navalis, “pertaining to ship”; cf. Greek ναῦς (naus), “ship”, ναύτης (nautes), “seaman, sailor”. The earliest attested form of the word is in the Mycenaean Greek compound word na-u-do-mo (*naudomoi), “shipbuilders”, written in Linear B syllabic script.[n 1]
The word formerly denoted fleets of both commercial and military nature. In modern usage “navy” used alone always denotes a military fleet, although the term “merchant navy” for a commercial fleet still incorporates the non-military word sense. This overlap in word senses between commercial and military fleets grew out of the inherently dual-use nature of fleets; centuries ago, nationality was a trait that unified a fleet across both civilian and military uses. Although nationality of commercial vessels has little importance in peacetime trade other than for tax avoidance, it can have greater meaning during wartime, when supply chains become matters of patriotic attack and defense, and when in some cases private vessels are even temporarily converted to military vessels. The latter was especially important, and common, before 20th-century military technology existed, when merely adding artillery and naval infantry to any sailing vessel could render it fully as martial as any military-owned vessel. Such privateering has been rendered obsolete in blue-water strategy since modern missile and aircraft systems grew to leapfrog over artillery and infantry in many respects; but privateering nevertheless remains potentially relevant in littoral warfare of a limited and asymmetric nature.
Naval warfare developed when humans first fought from water-borne vessels. Prior to the introduction of the cannon and ships with sufficient capacity to carry the large guns, navy warfare primarily involved ramming and boarding actions. In the time of ancient Greece and the Roman Empire, naval warfare centered on long, narrow vessels powered by banks of oarsmen (such as triremes and quinqueremes) designed to ram and sink enemy vessels or come alongside the enemy vessel so its occupants could be attacked hand-to-hand. Naval warfare continued in this vein through the Middle Ages until the cannon became commonplace and capable of being reloaded quickly enough to be reused in the same battle.
The Chola Dynasty of medieval India was known as one of the greatest naval powers of its time from 300 BC to 1279 AD. The Chola Navy, Chola kadarpadai comprised the naval forces of the Chola Empire along with several other Naval-arms of the country. The Chola navy played a vital role in the expansion of the Chola Tamil kingdom, including the conquest of the Sri Lanka islands, Kadaaram (Present day Burma), Sri Vijaya (present day Southeast Asia), the spread of Hinduism, Tamil architecture and Tamil culture to Southeast Asia and in curbing the piracy in Southeast Asia in 900 CE. In ancient China, large naval battles were known since the Qin Dynasty (also see Battle of Red Cliffs, 208), employing the war junk during the Han Dynasty. However, China’s first official standing navy was not established until the Southern Song dynasty in the 12th century, a time when gunpowder was a revolutionary new application to warfare.