A convoy of merchant ships protected
by airplanes en route to Cape Town during World War II
A
convoy is a group of
vehicles (of any type, but usually motor vehicles or
ships) traveling together for mutual support and protection. Often,
a convoy is organized with armed defensive support, though 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 used for hundreds of years, and examples of
merchant ships traveling under naval protection have been traced
back to the 12th Century. The use of organised naval convoys dates
from when ships began to be separated into specialist classes and
national navies were established.
By the
French Revolutionary
Wars of the late 18th century, effective
naval convoy
tactics had been developed to ward off
pirates and
privateers. Some convoy contained several hundred
merchant ships. The most enduring system of convoys were the
Spanish 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 no more likely
to be found than a single ship. Even if the privateer found a
convoy and the wind was favourable for an attack, it could 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 which sailed in convoys.
Many
naval battles in the
age of sail were fought around convoys,
including:
By the end of the
Napoleonic Wars
the
Royal Navy had in place a
sophisticated convoy system to protect merchant ships. Losses of
ships traveling out of convoy were so high that no merchant ship
was allowed to sail unescorted.
World War I
In the early 20th century, the
dreadnought changed the balance of
power in convoy battles. Steaming faster than merchant ships and
firing at long ranges, a single
battleship could 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 high cost.
Battleships were the main reason that the British
Admiralty did not adopt convoy tactics at the
start of the
first Battle
of the Atlantic in
World War I. But
the German capital ships had been bottled up in the North Sea, and
the main threat to shipping came from
U-boats. From a tactical point of view, World War
I-era
submarines were similar to
privateers in the age of sail: 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 convoy
was trialled, before being officially introduced in the Atlantic in
September 1917.
Other arguments against convoy 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 any escort at
all. 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 book
On 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. Also,
it should be noted that convoy duty exposes the escorting warships
to the uncomfortable and sometimes outright hazardous conditions of
the North Atlantic, but with only extremely rare occurrences of
visible achievement (i.e. fending off a submarine assault).
World War II
Convoy Routes 1941
The British adopted a convoy system, initially voluntary and later
compulsory for almost all merchant ships, the moment that
World War II was 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 the
second Battle of the Atlantic
was a long struggle as the Germans developed anti-convoy tactics
and the British developed counter-tactics to thwart the
Germans.
The power of a battleship against a convoy was dramatically
illustrated by the fate of
Convoy
HX-84. On November 5, 1940, the German pocket battleship
Admiral
Scheer encountered the convoy.
Maiden,
Trewellard,
Kenbame Head,
Beaverford,
and
Fresno were quickly sunk, and other ships were
damaged. Only the sacrifice of the
Armed Merchant Cruiser HMS Jervis Bay and failing
light allowed the rest of the convoy to escape.
The power of a battleship in protecting a convoy was also
dramatically illustrated when the German warships
Scharnhorst and
Gneisenau
came upon an eastbound British convoy of 41 ships,
HX-106 in the North Atlantic on February 8, 1941.
When they noticed the presence in the escort of the old battleship,
HMS Ramillies, they fled
the scene, rather than risk damage from her 15" 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 of
operational research in war.
On the entry of the U.S. into World War II, the U.S. Navy decided
not to instigate convoys on eastern seaboard of the U.S. Fleet
Admiral
Ernest King ignored 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 their
second happy
time, which did not end until convoys were introduced.
The German anti-convoy
tactics included:
- long-range surveillance aircraft to find convoys;
- strings of U-boats (wolf packs) 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:
They were also aided by
During
World War II, Japanese
vessels
rarely traveled in convoys. As a result, their merchant
fleet was
largely
destroyed by Allied submarines.
Many naval battles of World War II were fought around convoys,
including:
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 VII and
Type IX U-boat were 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
travelled 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-WWII
US Navy warships escort the tanker
Gas King in 1987
The largest convoy effort since World War II was
Operation Earnest Will, the
U.S. Navy's
1987–88 escort of reflagged Kuwaiti
tanker in the Persian Gulf
during the Iran–Iraq War.In the present
day, convoys are used as a tactic by navies to deter
pirates off the coast of Somalia from
capturing unarmed civilian freighters who would otherwise pose easy
targets.It seems that
satellite
surveillance,
aircraft carriers,
cruise missiles and modern submarines
have turned the tactical advantage decidedly in favour of the
attacker. See the
modern naval
tactics article for an idea of the problems facing the
defender.
Humanitarian aid convoys
The word, "convoy" is also associated with groups of road vehicles
being driven, mostly by volunteers, to deliver
humanitarian aid, supplies, and – a stated
objective in some cases – "solidarity".
In the
1990s these convoys became common travelling from Western Europe to countries of the former
Yugoslavia, in particular Bosnia
and Kosovo
, 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
as Romania
; and where
other disasters have led to problems, such as around the Chernobyl
disaster
in Belarus
and Ukraine
.
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 in Eastern
Europe and, in a few cases, North
Africa and even Iraq
. 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 as
United Nations
humanitarian efforts.
Truckers' convoys
The film
Convoy (inpsired by
a 1975
song of the same name) explores
the camaraderie between truck drivers, where the culture of the
CB radio encourages truck drivers to travel
in convoys.
Truckers' convoys were created as a byproduct of the 55 mph
speed limit and 18-wheelers becoming the prime targets of speed
traps. Most truckers had difficult schedules to keep and as a
result had to maintain a speed above the posted speed limit in
order to reach their destinations on time. Convoys were started so
that multiple trucks could run together at a high speed with the
thinking being that if they passed a speed trap the police would
only be able to pull over one of the trucks in the convoy. The
truckers convoy is more similar to the
caravan than to the military
convoy.
See also
Military convoys
Humanitarian convoys
References
- Convoy, The Defense of Sea Trade 1890-1990, John Winton 1983.
ISBN 0 7181 21635
External links
(1653)
(1781)
and La Rochelle
;
, November 1942
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