Convoy

For other uses, seeConvoy (disambiguation).

This article is about an organised group of separate vehicles traveling together. For connected vehicles, seeroad train.For an organised group of vehicles only following a lead, seemotorcade.For a group of separate vehicles where each follows another, seeplatoon (automobile).

A convoy ofU.S. Armytrucks inHawaii

Aconvoyis a group ofvehicles,typically motor vehicles or ships, traveling together for mutual support and protection. Often, a convoy is organized with armed defensive support and can help maintain cohesion within a unit. It may also be used in a non-military sense, for example when driving through remote areas.

Naval convoys

Age of Sail

Naval convoys have been in use for centuries, with examples of merchant ships traveling under naval protection dating to the 12th century.The use of organized naval convoys dates from when ships began to be separated into specialist classes and national navies were established.

By theFrench Revolutionary Warsof the late 18th century, effectivenavalconvoytacticshad been developed to ward offpiratesandprivateers.Some convoys contained several hundred merchant ships. The most enduring system of convoys were theSpanish treasure fleets,that sailed from the 1520s until 1790.

When merchant ships sailed independently, a privateer could cruise a shipping lane and capture ships as they passed. Ships sailing in convoy presented a much smaller target: a convoy was as hard to find as a single ship. Even if the privateer found a convoy and the wind was favourable for an attack, it could still hope to capture only a handful of ships before the rest managed to escape, and a small escort of warships could easily thwart it. As a result of the convoy system's effectiveness, wartime insurance premiums were consistently lower for ships that sailed in convoys.

Manynaval battlesin theAge of Sailwere fought around convoys, including:

• TheBattle of Portland(1653)
• TheBattle of Ushant (1781)
• TheBattle of Dogger Bank (1781)
• The Glorious First of June(1794)
• TheBattle of Pulo Aura(1804)

By the end of theNapoleonic Wars,theRoyal Navyhad in place a sophisticated convoy system to protect merchant ships.Losses of ships travelling out of convoy, however, were so high that no merchant ship was allowed to sail unescorted.

World War I

Main article:Convoys in World War I

In the early 20th century, thedreadnoughtchanged the balance of power in convoy battles. Steaming faster than merchant ships and firing at long ranges, a singlebattleshipcould destroy many ships in a convoy before the others could scatter over the horizon. To protect a convoy against a capital ship required providing it with an escort of another capital ship, at very highopportunity cost(i.e. potentially tying down multiple capital ships to defend different convoys against one opponent ship).

Battleships were the main reason that theBritish Admiraltydid not adopt convoy tactics at the start of thefirst Battle of the AtlanticinWorld War I.But the German capital ships had been bottled up in the North Sea, and the main threat to shipping came fromU-boats.From a tactical point of view, World War I–erasubmarineswere similar to privateers in the age of sail. These submarines were only a little faster than the merchant ships they were attacking, and capable of sinking only a small number of vessels in a convoy because of their limited supply of torpedoes and shells. The Admiralty took a long time to respond to this change in the tactical position, and in April 1917 convoys were trialled, before being officially introduced in the Atlantic in September 1917.

Other arguments against convoys were raised. The primary issue was the loss of productivity, as merchant shipping in convoy has to travel at the speed of the slowest vessel in the convoy and spent a considerable amount of time in ports waiting for the next convoy to depart. Further, large convoys were thought to overload port resources.

Actual analysis of shipping losses in World War I disproved all these arguments, at least so far as they applied to transatlantic and other long-distance traffic. Ships sailing in convoys were far less likely to be sunk, even when not provided with an escort. The loss of productivity due to convoy delays was small compared with the loss of productivity due to ships being sunk. Ports could deal more easily with convoys because they tended to arrive on schedule and so loading and unloading could be planned.

In his bookOn the Psychology of Military Incompetence,Norman Dixon suggested that the hostility towards convoys in the naval establishment were in part caused by a (sub-conscious) perception of convoys as effeminating, due to warships having to care for civilian merchant ships.Convoy duty also exposes the escorting warships to the sometimes hazardous conditions of the North Atlantic, with only rare occurrences of visible achievement (i.e. fending off a submarine assault).

World War II

See also:Convoys in World War II

Atlantic

See also:Battle of the Atlantic

Convoy routes in the Atlantic Ocean during 1941

The British adopted a convoy system, initially voluntary and later compulsory for almost all merchant ships, the moment thatWorld War IIwas declared. Each convoy consisted of between 30 and 70 mostly unarmed merchant ships.Canadian, and later American, supplies were vital for Britain to continue its war effort. The course of theBattle of the Atlanticwas a long struggle as the Germans developed anti-convoy tactics and the British developed counter-tactics to thwart the Germans.

The capability of a heavily armed warship against a convoy was dramatically illustrated by the fate ofConvoy HX 84.On November 5, 1940, the German heavy cruiserAdmiral Scheerencountered the convoy.Maiden,Trewellard,andKenbame Headwere quickly destroyed, andBeaverfordandFresno Cityfalling afterwards. Only the sacrifices of thearmed merchant cruiserHMSJervis Bayand the freighterBeaverfordto stall theScheer,in addition to failing light, allowed the rest of the convoy to escape.

The deterrence value of a battleship in protecting a convoy was also dramatically illustrated when the German light battleships (referred by some as battlecruisers)ScharnhorstandGneisenau,mounting 11 in (28 cm) guns, came upon an eastbound British convoy (HX 106,with 41 ships) in the North Atlantic on February 8, 1941. When the Germans detected the slow but well-protected battleshipHMSRamilliesescorting the convoy, they fled the scene rather than risk damage from her 15 in (38 cm) guns.

The enormous number of vessels involved and the frequency of engagements meant that statistical techniques could be applied to evaluate tactics: an early use ofoperational researchin war.

Prior to overt participation in World War II, the US was actively engaged in convoys with the British in the North Atlantic Ocean, primarily supporting British activities in Iceland.

After Germany declared war on the US, the US Navy decided not to organize convoys on the American eastern seaboard. US Fleet AdmiralErnest Kingignored advice on this subject from the British, as he had formed a poor opinion of the Royal Navy early in his career. The result was what the U-boat crews called theirSecond Happy Time,which did not end until convoys were introduced.

Pacific

See also:Pacific War

In the Pacific Theater of World War II,Japanesemerchant ships rarely traveled in convoys. Japanese destroyers were generally deficient in antisubmarine weaponry compared to their Allied counterparts, and the Japanese navy did not develop an inexpensive convoy escort like the Allies'destroyer escort/frigateuntil it was too late. In the early part of the conflict, American submarines in the Pacific were ineffective as they suffered from timid tactics, faulty torpedoes, and poor deployment, while there were only small numbers of British and Dutch boats. U.S. AdmiralCharles A. Lockwood's efforts, coupled with strenuous complaints from his captains, rectified these problems and U.S. submarines became much more successful by war's end. As a result, the Japanese merchant fleet waslargely destroyedby the end of the war. Japanese submarines, unlike their U.S. and German equivalents, focused on U.S. battle fleets rather than merchant convoys, and while they did manage some early successes, sinking two U.S. carriers, they failed to significantly inhibit the invasion convoys carrying troops and equipment in support of the U.S. island-hopping campaign.

Several notable battles in the South Pacific involved Allied bombers interdicting Japanese troopship convoys which were often defended by Japanese fighters, notableGuadalcanal(13 November 1942),Rabaul(5 January 1943), and theBattle of the Bismarck Sea(2–4 March 1943).

At theBattle off Samar,the effectiveness of the U.S. Navy's escorts was demonstrated when they managed to defend their troop convoy from a much larger and more powerful Japanese battle-fleet. The Japanese force comprised four battleships and numerous heavy cruisers, while the U.S. force consisted of escort carriers, destroyers, and destroyer escorts. Large numbers of American aircraft (albeit without much anti-ship ordnance other than torpedoes) and aggressive tactics of the destroyers (with their radar-directed gunfire) allowed the U.S. to sink three Japanese heavy cruisers at the cost of one escort carrier and three destroyers.

Tactics

A convoy of merchant ships protected by airplanesen routetoCape TownduringWorld War II

The German anti-convoytacticsincluded:

• long-range surveillance aircraft to find convoys;
• strings of U-boats (wolfpacks) that could be directed onto a convoy by radio;
• breaking the British naval codes;
• improved anti-ship weapons, including magnetic detonators and sonic homing torpedoes.

The Allied responses included:

• air raidson the U-boat bases atBrestandLa Rochelle;
• converted merchant ships, e.g.,Merchant aircraft carriers,Catapult Aircraft Merchantmanandarmed merchant cruisers
• Q-ships,submarine-hunters disguised as unarmed merchant ships to lure submarines into an attack
• more convoy escorts, including cheaply produced yet effectivedestroyer escorts/frigates(ascorvetteswere meant as a stopgap), andescort carriers;
• fighter aircraft (carried by escort carriers and merchant aircraft carriers) that would drive off German bombers and attack U-boats
• long-range aircraft patrols to find and attack U-boats;
• improved anti-submarine weapons such as thehedgehog;
• larger convoys, allowing more escorts per convoy as well as the extraction of enough escorts to form hunter-killer support groups that were not attached to a particular convoy
• allocating vessels to convoys according to speed, so that faster ships were less exposed.

They were also aided by

• improvedsonar(ASDIC) allowing escort vessels to better track U-boats;
• breaking theGerman naval cipher;
• improvedradarandradio direction findingallowing planes to find and destroy U-boats;
• improved escort anti-submarine tactics developed by theWestern Approaches Tactical Unit

Convoy battles

Many naval battles of World War II were fought around convoys, including:

• Convoy PQ 16,May 1942
• Convoy PQ 17,June–July 1942
• Convoy PQ 18,September 1942
• Operation Pedestal,August 1942
• TheNaval Battle of Guadalcanal,November 1942
• TheBattle of the Barents Sea,December 1942
• TheBattle of the Bismarck Sea,March 1943

The convoy prefix indicates the route of the convoy. For example, 'PQ' would be Iceland to Northern Russia and 'QP' the return route.

Analysis

The success of convoys as an anti-submarine tactic during the world wars can be ascribed to several reasons related to U-boat capabilities, the size of the ocean and convoy escorts.

In practice,Type VIIandType IX U-boatswere limited in their capabilities. Submerged speed and endurance was limited and not suited for overhauling many ships. Even a surfaced U-boat could take several hours to gain an attack position. Torpedo capacity was also restricted to around fourteen (Type VII) or 24 (Type IX), thus limiting the number of attacks that could be made, particularly when multiple firings were necessary for a single target. There was a real problem for the U-boats and their adversaries in finding each other; with a tiny proportion of the ocean in sight, without intelligence or radar, warships and even aircraft would be fortunate in coming across a submarine. The Royal Navy and later the United States Navy each took time to learn this lesson. Conversely, a U-boat's radius of vision was even smaller and had to be supplemented by regular long-range reconnaissance flights.

For both major allied navies, it had been difficult to grasp that, however large a convoy, its "footprint" (the area within which it could be spotted) was far smaller than if the individual ships had traveled independently. In other words, a submarine had less chance of finding a single convoy than if it were scattered as single ships. Moreover, once an attack had been made, the submarine would need to regain an attack position on the convoy. If, however, an attack were thwarted by escorts, even if the submarine had escaped damage, it would have to remain submerged for its own safety and might only recover its position after many hours' hard work. U-boats patrolling areas with constant and predictable flows of sea traffic, such as the United States Atlantic coast in early 1942, could dismiss a missed opportunity in the certain knowledge that another would soon present itself.

The destruction of submarines required their discovery, an improbable occurrence on aggressive patrols, by chance alone. Convoys, however, presented irresistible targets and could not be ignored. For this reason, the U-boats presented themselves as targets to the escorts with increasing possibility of destruction. In this way, the Ubootwaffe suffered severe losses, for little gain, when pressing pack attacks on well-defended convoys.

Post-World War II

U.S. Navyvessels escorting thetankerGas Kingin 1987

The largest convoy effort since World War II wasOperation Earnest Will,theU.S. Navy's1987–88 escort of reflaggedKuwaititankersin thePersian Gulfduring theIran–Iraq War.

In the present day, convoys are used as a tactic by navies to deterpirates off the coast of Somaliafrom capturing unarmed civilian freighters who would otherwise pose easy targets if they sailed alone.

Road convoys

A convoy ofStrykerstraveling betweenIraqandKuwaitduring theIraq Warin 2010

Humanitarian aid convoys

The word "convoy" is also associated with groups of road vehicles being driven, mostly by volunteers, to deliverhumanitarian aid,supplies, and—a stated objective in some cases— "solidarity".

In the 1990s these convoys became common traveling fromWestern Europeto countries of the formerYugoslavia,in particularBosniaandKosovo,to deal with the aftermath of the wars there. They also travel to countries where standards of care in institutions such as orphanages are considered low by Western European standards, such asRomania;and where other disasters have led to problems, such as around theChernobyl disasterinBelarusandUkraine.

The convoys are made possible partly by the relatively small geographic distances between the stable and affluent countries of Western Europe, and the areas of need inEastern Europeand, in a few cases,North Africaand evenIraq.They are often justified because although less directly cost-effective than mass freight transport, they emphasise the support of large numbers of small groups, and are quite distinct from multinational organisations such asUnited Nationshumanitarian efforts.

Truckers' convoys

A convoy of civilian trucks waiting forsecurity forcesto secure a stretch of road inAfghanistan

Truckers' convoys consisting ofsemi-trailer trucksand/orpetrol tankersare more similar to acaravanthan a military convoy.

Truckers' convoys were created as a byproduct of the U.S.'national 55 mph speed limitand 18-wheelers becoming the prime targets ofspeed traps.Most truckers had difficult schedules to keep and as a result had to maintain a speed above the posted speed limit to reach their destinations on time. Convoys were started so that multiple trucks could run together at a high speed with the rationale being that if they passed a speed trap the police would only be able to pull over one of the trucks in the convoy. When driving on a highway, convoys are also useful to conserve fuel bydrafting.

The filmConvoy,inspired by a 1975song of the same name,explores the camaraderie betweentruck drivers,where the culture of theCB radioencourages truck drivers to travel in convoys.

Truck convoys are sometimes organized forfundraising,charity,or promotional purposes. They can also be used as a form ofprotest,such as theCanada convoy protestin 2022.

Special convoy rights

3. Einsatzeinheit ofGerman Red CrossFreiburg Land preparing for a march under special convoy rights

The Highway Code of several European countries (Norway, Italy, Greece, Netherlands, Germany, Austria, Switzerland, possibly more) includes special rights for marked convoys. They have to be treated like a single vehicle. If the first vehicle has passed an intersection, all others may do so without interruption. If other road users overtake the convoy, they are not allowed to split into the queue. Clear and uniform marking has been required in court decisions for these rights to apply. Operating such convoy usually needs special permission, but there are exemptions for emergency and catastrophe intervention. Common practice is, to operate with the same style of marking as NATO convoys:STANAG2154 marking plus country-specific augmentation listed in Annex B to the STANAG.

During theCold Warwith its high number of military exercises, the military was the main user of convoy rights. Today, catastrophes like large-scale flooding might bring a high number of flagged convoys to the roads. Large-scale evacuations for the disarming of World War II bombs are another common reason fornon-governmental organization(NGO) unit movements under convoy rights.

Storm convoys

In Norway, "convoy driving" (Norwegian:kolonnekjøring) is used during winter in case weather is too bad for vehicles to pass on their own. Convoy driving is initiated when the strong wind quickly fills the road with snow behind snowplows, particularly on mountain passes.Only a limited number of vehicles are allowed for each convoy and convoy leader is obliged to decline vehicles not fit for the drive.Storm convoys are prone tomultiple-vehicle collision.Convoy driving is used throughHardangerviddapass onroad 7during blizzards.Convoy is sometimes used on road E134 at the highest and most exposed sections during bad weather.OnEuropean route E6throughSaltfjelletpass convoy driving is often used when wind speed is over 15–20 m/s (fresh or strong gale) in winter conditions. During the winter of 1990 there was convoy driving for almost 500 hours at Saltfjellet

See also

• Camel train
• Motorcade
• Police escort
• Road train
• Shoaling and schooling
• Wagon train

Further reading

• Allard, Dean C. "Anglo-American Naval Differences During World War I."Military Affairs: The Journal of Military History, Including Theory and Technology(1980): 75–81. in JSTOR
• Crowhurst, R. Patrick. "The Admiralty and the Convoy System in the Seven Years War."The Mariner's Mirror(1971) 57#2 pp: 163–173.
• Gasslander, Olle. "The convoy affair of 1798."Scandinavian Economic History Review2.1 (1954): 22–30.abstract
• Herwig, Holger H., and David F. David. "The Failure of Imperial Germany's Undersea Offensive Against World Shipping, February 1917–October 1918."Historian(1971) 33#4 pp: 611–636.online
• Lewis, James Allen.The Spanish convoy of 1750: heaven's hammer and international diplomacy(Univ Press of Florida, 2009)
• Syrett, David. "The Organization Of British Trade Convoys during the American War, 1775–1783."The Mariner's Mirror(1976) 62#2 pp: 169–181.abstract
• Thompson, F. J. "The Merchant Ship in Convoy."The RUSI Journal79.513 (1934): 69–86.

Primary sources

• Connor, Guy, and Jeffrey L. Patrick. "On Convoy Duty in World War I: The Diary of Hoosier Guy Connor."Indiana Magazine of History(1993).online

World War II

• Edwards, Bernard.The road to Russia: Arctic convoys 1942(Leo Cooper Books, 2002)
• Forczyk, Robert.Fw 200 Condor Vs Atlantic Convoy, 1941–1943(Osprey Publishing, 2010)
• Hague, Arnold.The allied convoy system, 1939–1945: its Organization, Defence and Operation(Naval Institute Press, 2000)
• Kaplan, Philip, and Jack Currie.Convoy: merchant sailors at war, 1939–1945(Aurum Press, 1998)
• Middlebrook, Martin.Convoy: the Battle for Convoys SC. 122 and HX. 229(Allen Lane, 1976)
• Milner, Marc. "Convoy Escorts: Tactics, Technology and Innovation in the Royal Canadian Navy, 1939–1943." Military Affairs: The Journal of Military History, Including Theory and Technology (1984): 19–25.
• O'Hara, Vincent P.In Passage Perilous: Malta and the Convoy Battles of June 1942(Indiana University Press, 2012)
• Smith, Peter Charles.Arctic Victory: The Story of Convoy PQ 18(Kimber, 1975)
• Winton, John.Convoy, The Defense of Sea Trade 1890–1990,1983.ISBN0-7181-2163-5

Official history

• Commander in Chief, United States Fleet, "Convoy and Routing." Washington, 1945. 147 pp.,online

External links

• Lists of convoy prefixes for both World Wars
• Convoy web– a comprehensive analysis of certain naval convoy routes
• Aid Convoy– a humanitarian aid charity running convoys