Convoy in the context of "Battle of the Atlantic"

HMS Greyhound was a G-class destroyer built for the Royal Navy in the 1930s. Greyhound participated in the Norwegian Campaign in April 1940, the Dunkirk evacuation in May and the Battle of Dakar in September before being transferred to the Mediterranean Fleet in November. The ship generally escorted the larger ships of the Mediterranean Fleet as they protected convoys against attacks from the Italian Fleet. She sank two Italian submarines while escorting convoys herself in early 1941. Greyhound was sunk by German Junkers Ju 87 Stuka dive bombers north-west of Crete on 22 May 1941 as she escorted the battleships of the Mediterranean Fleet attempting to intercept the German sea-borne invasion forces destined for Crete.

An aircraft catapult is an acceleration device used to help fixed-wing aircraft reach liftoff speed (V_LOF) faster during takeoff, typically when trying to take off from a very short runway, as otherwise the aircraft engines alone cannot get the aircraft to sufficient airspeed quickly enough for the wings to generate the lift needed to sustain flight. Launching via catapults enables aircraft that typically are only capable of conventional takeoffs, especially heavier aircraft with significant payloads, to perform short takeoffs from the roll distances of light aircraft. Catapults are usually used on the deck of a ship — such as the flight deck of an aircraft carrier — as a form of assisted takeoff for navalised aircraft, but can also be installed on land-based runways, although this is rare.

Historically it was most common for seaplanes (which have pontoons instead of wheeled landing gears and thus cannot utilize runways) to be catapulted from ships onto nearby water for takeoff, allowing them to conduct aerial reconnaissance missions and be crane-hoisted back on board during retrieval, although by the late First World War their roles are largely supplanted by the more versatile biplanes that can take off and land on carrier decks unassisted. During the Second World War before the advent of escort carriers, monoplane fighter aircraft (notably the Hawker Hurricane) would sometimes be catapulted from "catapult-equipped merchant" (CAM) vessels for one-way sorties to repel enemy aircraft harassing shipping lanes, forcing the returning pilot to either divert to a land-based airstrip, jump out by parachute, or ditch in the water near the convoy and wait for rescue. By the time fleet carriers became the norm in WW2, catapult launches have become largely unnecessary and carrier-based fighter-bombers would routinely perform self-powered takeoffs and landings off and onto carrier decks, especially during the naval aviation-dominated Pacific War between the United States and the Empire of Japan. However, escalating arms races during the Cold War accelerated the adoption of the heavier jet aircraft for naval operations, thus motivating the development of new catapult systems, especially after the popularization of angled flight decks further limited the practical distance available as takeoff runways. Nowadays, jet aircraft can launch from aircraft carriers via either catapults or ski-jump deck, and perform optics-assisted landing onto the same ship with help from decelerative arresting gears.

During the 18th and 19th centuries, a sloop-of-war was a warship of the Royal Navy with a single gun deck that carried up to 18 guns. The rating system of the Royal Navy covered all vessels with 20 or more guns; thus, the term encompassed all unrated warships, including gun-brigs and cutters. In technical terms, even the more specialised bomb vessels and fire ships were classed by the Royal Navy as sloops-of-war, and in practice these were employed in the role of a sloop-of-war when not carrying out their specialised functions.

In World War I and World War II, the Royal Navy reused the term "sloop" for specialised convoy-defence vessels, including the Flower class of the First World War and the highly successful Black Swan class of the Second World War, with anti-aircraft and anti-submarine capabilities. They performed similar duties to the destroyer escorts of the United States Navy, and also performed similar duties to the smaller corvettes of the Royal Navy.

The convoy—a group of merchantmen or troopships traveling together with a naval escort—was revived during World War I (1914–18), after having been discarded at the start of the Age of Steam. Although convoys were used by the Royal Navy in 1914 to escort troopships from the Dominions, and in 1915 by both it and the French Navy to cover their own troop movements for overseas service, they were not systematically employed by any belligerent navy until 1916. The Royal Navy was the major user and developer of the modern convoy system, and regular transoceanic convoying began in June 1917 with the assistance of the US and other Allied navies. They made heavy use of aircraft for escorts, especially in coastal waters, an obvious departure from the convoy practices of the Age of Sail.

As historian Paul E. Fontenoy put it, "[t]he convoy system defeated the German submarine campaign." From June 1917 on, the Germans were unable to meet their set objective of sinking 600,000 long tons (610,000 t) of enemy shipping per month. In 1918, they were rarely able to sink more than 300,000 long tons (300,000 t). Between May 1917 and the end of the war on 11 November 1918, only 154 of 16,539 vessels convoyed across the Atlantic had been sunk, of which 16 were lost through the natural perils of sea travel and a further 36 because they were stragglers.

The Spanish treasure fleet, or West Indies Fleet (Spanish: Flota de Indias, also called silver fleet or plate fleet; from the Spanish: plata meaning "silver"), was a convoy system of sea routes organized by the Spanish Empire from 1566 to 1790, which linked Spain with its territories in the Americas across the Atlantic. The convoys were general purpose cargo fleets used for transporting a wide variety of items, including agricultural goods, lumber, various metal resources such as silver and gold, gems, pearls, spices, sugar, tobacco, silk, and other exotic goods from the overseas territories of the Spanish Empire to the Spanish mainland. Spanish goods such as oil, wine, textiles, books and tools were transported in the opposite direction.

The West Indies fleet was the first permanent transatlantic trade route in history. Similarly, the related Manila galleon trade was the first permanent trade route across the Pacific. The Spanish West and East Indies fleets are considered among the most successful naval operations in history and, from a commercial point of view, they made possible key components of today's global economy.

In naval terminology, a destroyer is a fast, maneuverable, long-endurance warship intended to escortlarger vessels in a fleet, convoy, or carrier battle group and defend them against a wide range of general threats. They were conceived in the late 19th century as a defense against torpedo boats, and by the time of the Russo-Japanese War in 1904, these "torpedo boat destroyers" (TBDs) were "large, swift, and powerfully armed torpedo boats designed to destroy other torpedo boats". Although the term "destroyer" had been used interchangeably with "TBD" and "torpedo boat destroyer" by navies since 1892, the term "torpedo boat destroyer" had been generally shortened to simply "destroyer" by nearly all navies by the First World War.

Before World War II, destroyers were light vessels with little endurance for unattended ocean operations; typically, a number of destroyers and a single destroyer tender operated together. After the war, destroyers grew in size. The American Allen M. Sumner-class destroyers had a displacement of 2,200 tons, while the Arleigh Burke class has a displacement of up to 9,600 tons, a difference of nearly 340%. Moreover, the advent of guided missiles allowed destroyers to take on the surface-combatant roles previously filled by battleships and cruisers. This resulted in larger and more powerful guided missile destroyers more capable of independent operation.

The Malta convoys were Allied supply convoys of the Second World War. The convoys took place during the Siege of Malta in the Mediterranean Theatre. Malta was a base from which British sea and air forces could attack ships carrying supplies from Europe to Italian Libya. Britain fought the Western Desert Campaign against Axis armies in North Africa to keep the Suez Canal and to control Middle Eastern oil. The strategic value of Malta was so great the British risked many merchant vessels and warships to supply the island and the Axis made determined efforts to neutralise the island as an offensive base.

The civilian population and the garrison required imports of food, medical supplies, fuel and equipment; the military forces on the island needed reinforcements, ammunition and spare parts. British convoys were escorted to Malta by ships of the Mediterranean Fleet, Force H and aircraft of the Fleet Air Arm and Royal Air Force, during the Battle of the Mediterranean (1940–1943). British and Allied ships were attacked by the Italian Regia Aeronautica (Royal Air Force) and Regia Marina (Royal Navy) in 1940 and from 1941, by the Luftwaffe (German Air Force) and Kriegsmarine (German Navy).

De Grasse is one of three Tourville-class guided-missile frigates built for the French Marine Nationale during the Cold War. They were designed as convoy escorts.