Antisubmarine Warfare

---

In a post-war analysis of U boat losses, mines accounted for at least 94 of the U boats sunk. The final passive measure against submarines was camouflage. This resulted in ships being painted in what now seem bizarre patterns designed to confuse a submarine as to the direction in which the ship was heading, as well as its size and speed. Throughout the war submarines had to spend most of their time on the surface, because submerged they relied on battery power for propulsion which resulted in low speed and short endurance.

Thus on the surface they could recharge their batteries and proceed at higher speed. The first offensive measure against the submarine threat was by instituting patrols by surface ships and aircraft. However, in the event that a submarine was found, destroying it was not easy. Gunfire was at first the only longer range method, but was only effective while the submarine was on the surface. Ramming was also effective if the vessel could get close enough before the submarine submerged, but usually also resulted in major damage to the patrol vessel.

Anti-Submarine Warfare

Later depth charges were introduced which gave the possibility of sinking a recently submerged submarine. When on patrol the aircraft would be directed to patrol specific sectors of the grid. To destroy any submarine they found, small bombs were carried. A development of the patrol ships was to either convert merchant ships or build ships to resemble merchant ships. Although manned by men of great courage and dedication the or so decoy ships only sank ten submarines. The first effective anti-submarine weapon for use against a submerged submarine was the depth charge. This had been first proposed in , but was not at sea in any numbers until The depth charge was an iron drum containing pounds 68 kg of explosive, activated at a pre-determined depth.

At first the depth charge was activated by a rope, setting off the charge when it came taut, but a hydrostatic pistol was soon introduced.

Seaplanes and airships were also used to patrol for submarines. A number of successful attacks were made, [a] but the main value of air patrols was in driving the U-boat to submerge, rendering it virtually blind and immobile.

To attack submerged boats a number of anti-submarine weapons were derived, including the sweep with a contact-fused explosive. Bombs were dropped by aircraft and depth charge attacks were made by ships. Prior to the introduction of dedicated depth charge throwers, charges were manually rolled off the stern of a ship. The Q-ship , a warship disguised as a merchantman, was used to attack surfaced U-boats while the R1 was the first ASW submarine.

A major contribution was the interception of German submarine radio signals and breaking of their code by Room 40 of the Admiralty.

Navigation menu

This period saw the development of active sonar ASDIC and its integration into a complete weapons system by the British, as well as the introduction of radar. During the period, there was a great advance due to the introduction of electronics for amplifying, processing, and displaying signals. In particular, the "range recorder" was a major step that provided a memory of target position. Because the propellers of many submarines were extremely loud in the water [ citation needed ] though it doesn't seem so from the surface , range recorders were able to gauge the distance from the U-boat by sound.

This would allow mines or bombs around that area to be detonated. New materials for sound projectors were developed. Both the Royal Navy and the U. Navy fitted their destroyers with active sonars. In , a small escort ship was designed and plans made to arm trawlers and to mass-produce ASDIC sets. Depth sounders were developed that allowed measurement by moving ships and an appreciation obtained of the properties of the ocean affecting sound propagation.

The bathythermograph was invented in , which was soon fitted to ASW ships. There were few major advances in weapons. However, the performance of torpedoes continued to improve. During the Second World War , the submarine menace revived, threatening the survival of island nations like Britain and Japan which were particularly vulnerable because of their dependence on imports of food, oil, and other vital war materials.

Despite this vulnerability, little had been done to prepare sufficient anti-submarine forces or develop suitable new weapons. Other navies were similarly unprepared, even though every major navy had a large, modern submarine fleet, because all had fallen in the grip of Mahanian doctrine which held guerre de course could not win a war.

At the beginning of the war, most navies had few ideas how to combat submarines beyond locating them with sonar and then dropping depth charges on them. Sonar proved much less effective than expected, and was no use at all against submarines operating on the surface, as U-boats routinely did at night. Indicator loop technology was quickly developed further and deployed by the US Navy in By then there were dozens of loop stations around the world.

Sonar was far more effective and loop technology died straight after the war. The use and improvement of radar technology was one of the most important proponents in the fight against submarines.

Locating submarines was the first step in being able to defend against and destroy them. Throughout the war, Allied radar technology was much better than their German counterparts. German U-Boats struggled to have proper radar detection capabilities and keep up with the successive generations of Allied airborne radar.

The first generation of Allied airborne radar used a 1. By the second half of the " Metox " radar detector was used by U-boats to give some warning from airborne attack. In the Allies began to deploy aircraft equipped with new cavity magnetron-based centimeter wavelength radar ASV III , which was undetectable by "Metox", in sufficient numbers to yield good results. Eventually the "Naxos" radar detector was fielded that could detect cm wavelength radar, but it had a very short range and only gave a U-Boat limited time to dive.

Navy approach , and to divert vulnerable or valuable ships away from known U-boat concentrations. During the Second World War , the Allies developed a huge range of new technologies, weapons and tactics to counter the submarine danger. Many different aircraft from airships to four-engined sea- and land-planes were used. As more patrol planes became equipped with radar, U-Boats began to be surprised at night by aircraft attacks.

U-Boats were not defenseless, since their deck guns were a very good anti-aircraft weapon. They claimed Allied aircraft shot down for the loss of U-boats to air attack. The German naval command struggled to find a solution to the aircraft attacks. At one point in the war, there was even a 'shoot back order' requiring U-boats to stay on the surface and fight back, in the absence of any other option.

Some commanders started charging batteries during the day to gain more warning from air attack, and perhaps gain time to submerge.

Subcategories

One solution was the snorkel, which allowed a U-boat to stay submerged and still charge its batteries. A snorkel made a U-boat more survivable and losses to aircraft went down. The provision of air cover was essential. The Germans at the time had been using their Focke-Wulf Fw "Condor" long range aircraft to attack shipping and provide reconnaissance for U-boats, and most of their sorties occurred outside the reach of existing land-based aircraft that the Allies had; this was dubbed the Mid-Atlantic gap. At first, the British developed temporary solutions such as CAM ships and merchant aircraft carriers.

These were superseded by mass-produced, relatively cheap escort carriers built by the United States and operated by the US Navy and Royal Navy. There was also the introduction of long-ranged patrol aircraft. Many U-boats feared aircraft, as the mere presence would often force them to dive, disrupting their patrols and attack runs. The Americans favored aggressive hunter-killer tactics using escort carriers on search and destroy patrols, whereas the British preferred to use their escort carriers to defend the convoys directly.

The American view was that defending convoys did little to reduce or contain U-boat numbers, while the British were constrained by having to fight the battle of the Atlantic alone for the early part of the war with very limited resources. There were no spare escorts for extensive hunts, and it was only important to neutralize the U-boats which were found in the vicinity of convoys. The survival of convoys was critical, and if a hunt missed its target a convoy of strategic importance could be lost.

The British also reasoned that since submarines sought convoys, convoys would be a good place to find submarines. Once America joined the war, the different tactics were complementary, both suppressing the effectiveness of and destroying U-boats. The increase in Allied naval strength allowed both convoy defense and hunter-killer groups to be deployed, and this was reflected in the massive increase in U-boat kills in the latter part of the war. The British developments of centimetric radar and the Leigh Light , as well as increased numbers of escorts, reached the point of being able to support U-boat hunting towards the end of the war, while earlier on, the advantage was definitely on the side of the submarine.

Commanders such as F. Walker developed a creeping attack technique, where one destroyer would track the U-boat while another attacked.

Anti-submarine warfare

Often U-boats would turn and increase speed to spoil the depth charge attack, as the escort would lose sonar contact as it steamed over the submarine. With the new tactic, one escort vessel would attack while another would track the target. Any course or depth change could be relayed to the attacking destroyer. Once a U-boat was caught, it was very difficult to escape.

Category:Anti-submarine warfare

Since Hunter-Killer groups were not limited to convoy escort, they could continue an attack until a U-Boat was destroyed or had to surface from damage or lack of air. The earliest recorded sinking of one submarine by another while both were submerged occurred in when HMS Venturer torpedoed U off the coast of Norway. The captain of Venturer tracked U on hydrophones for several hours and manually calculated a three-dimensional firing solution before launching four torpedoes.

Italian and German submarines operated in the Mediterranean on the Axis side while French and British submarines operated on the side of the Allies. German subs first had to pass through the highly defended Straits of Gibraltar , where 9 were sunk, and a similar number damaged so severely they had to limp back to base. The Mediterranean is calmer than the Atlantic, which made escape for U-Boats more difficult and was ringed with Allied air bases.

Similar ASW methods were used as in the Atlantic but an additional menace was the use by Italians of midget submarines. Operating under the same clear-water conditions in the Mediterranean - such that British submarines were painted dark blue on their upper surfaces to make them less visible from the air when submerged at periscope depth - the Royal Navy, mostly operating from Malta , lost 41 submarines to the opposing German and Italian forces, including HMS Upholder and HMS Perseus. Japanese submarines pioneered many innovations, being some of the largest and longest range vessels of their type and were armed with the Type 95 torpedo.

However, they ended up having little impact, especially in the latter half of the war. Instead of commerce raiding like their U-boat counterparts, they followed the Mahanian doctrine, serving in offensive roles against warships, which were fast, maneuverable and well-defended compared to merchant ships. Once the US was able to ramp up construction of destroyers and destroyer escorts , as well as bringing over highly effective anti-submarine techniques learned from the British from experiences in the Battle of the Atlantic , they would take a significant toll on Japanese submarines, which tended to be slower and could not dive as deep as their German counterparts.

Japanese submarines, in particular, never menaced the Allied merchant convoys and strategic shipping lanes to any degree that German U-boats did. One major advantages the Allies had was the breaking of the Japanese "Purple" code by the US, so allowing friendly ships to be diverted from Japanese submarines and allowing Allied submarines to intercept Japanese forces.

In and early , US submarines posed little threat to Japanese ships, whether warships or merchant ships. They were initially hampered by poor torpedoes, which often failed to detonate on impact, ran too deep, or even ran wild.

As the US submarine menace was slight in the beginning, Japanese commanders became complacent and as a result did not invest heavily into ASW measures or upgrade their convoy protection to any degree to what the Allies in the Atlantic did. Often encouraged by the Japanese not placing a high priority on the Allied submarine threat, US skippers were relatively complacent and docile compared to their German counterparts, who understood the "life and death" urgency in the Atlantic.

Lockwood pressured the ordnance department to replace the faulty torpedoes; famously when they initially ignored his complaints, he ran his own tests to prove the torpedoes' unreliability. He also cleaned out the "deadwood", replacing many cautious or unproductive submarine skippers with younger somewhat and more aggressive commanders. As a result, in the latter half of , US subs were suddenly sinking Japanese ships at a dramatically higher rate, scoring their share of key warship kills and accounting for almost half of the Japanese merchant fleet.

Japan's naval command was caught off guard; Japan had neither the anti-submarine technology or doctrine, nor the production capability to withstand a tonnage war of attrition , nor did she develop the organizations needed unlike the Allies in the Atlantic. Japanese antisubmarine forces consisted mainly of their destroyers, with sonar and depth charges. However, Japanese destroyer design, tactics, training, and doctrine emphasized surface nightfighting and torpedo delivery necessary for fleet operations over anti-submarine duties.

By the time Japan finally developed a destroyer escort , which was more economical and better suited to convoy protection, it was too late; coupled to incompetent doctrine and organization, [c] it could have had little effect in any case.

• La prison (French Edition)
• Jenkins Girls: Ladies First
• Dallippopotamo in su (Italian Edition)
• Drácula (Narrativa 74 nº 1) (Spanish Edition)
• Baby Now That Ive Found You
• A Short Introduction to Robert E. Lee (Illustrated)