Convoy

A convoy is a group of vehicles traveling together for mutual support and protection. This term usually applies to motor vehicles or ships. In military settings, convoys often include armed defensive support. This organization helps a unit maintain cohesion while moving. Convoys are also used in non-military ways, such as driving through remote areas.

The mechanism of a convoy relies on grouping targets to increase safety. When merchant ships sail alone, they are easy targets for privateers. A privateer can cruise a shipping lane and capture individual ships. In a convoy, the group is as hard to find as a single ship. If an attacker finds the group, they might only capture a few vessels. The remaining ships can then use the distraction to escape. Small groups of warships acting as escorts can also thwart attacks. This system makes wartime insurance premiums lower because the risk is reduced.

Naval convoys have a very long history. Merchant ships used naval protection as far back as the 12th century. One of the most enduring systems was the Spanish treasure fleets. These fleets sailed from the 1520s until 1790. By the late 18th century, effective tactics helped ward off pirates and privateers. Many famous naval battles occurred around convoys. These include the Battle of Portland in 1653 and the Battle of Ushant in 1781. By the end of the Napoleonic Wars, the Royal Navy had a very sophisticated system.

In the early 20th century, technology changed the nature of convoy battles. The dreadnought, a powerful type of battleship, changed the balance of power. These ships were faster than merchant vessels and could fire at long ranges. A single battleship could destroy many ships in a convoy before they scattered. Because of this, the British Admiralty did not use convoys at the start of World War I. They feared the high cost of protecting convoys with capital ships. However, the main threat in the Atlantic was actually U-boats, or submarines.

Submarines in World War I were tactically similar to the privateers of the past. They were only slightly faster than merchant ships. They also had a limited supply of torpedoes and shells. This meant they could only sink a small number of vessels in a convoy. The British Admiralty finally introduced official convoys in the Atlantic in September 1917. There were many arguments against this move. Some leaders worried about a loss of productivity. They believed convoys were too slow because they moved at the speed of the slowest ship. Others feared that large groups would overload port resources.

Actual analysis during World War I disproved these concerns. Ships in convoys were far less likely to be sunk. The delay in productivity was small compared to the loss of ships being sunk. Ports actually found convoys easier to manage because they arrived on schedule. During World War II, the British made convoys compulsory for almost all merchant ships. Atlantic convoys typically consisted of 30 to 70 mostly unarmed merchant ships.

The Battle of the Atlantic was a long struggle of tactics. Germany used "wolfpacks," which were strings of U-boats directed by radio. They also used long-range surveillance aircraft and improved torpedoes. The Allies responded with many new tools. They used escort carriers, which are small aircraft carriers. They also used "Q-ships," which were submarine-hunters disguised as unarmed merchant ships. Other tools included the hedgehog, an anti-submarine weapon, and improved sonar called ASDIC.

In the Pacific Theater, the situation was different. Japanese merchant ships rarely traveled in convoys. This made them easier targets for American submarines. By the end of the war, U.S. submarine success helped destroy the Japanese merchant fleet. The U.S. Navy also used escorts to protect troop convoys. At the Battle off Samar, U.S. escorts successfully defended a troop convoy. They faced a much larger Japanese battle-fleet. Using aircraft and aggressive destroyer tactics, the U.S. sank three heavy cruisers. This showed how effective even small escort forces could be.