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ANTONY PRESTON, JOHN BATCHELOR
American Gato. The USS Gato was the lead ship of a class authorised in 1941, before the United States entered the war. Over 200 of this very good design were ordered by 1945, and they were the backbone of the US Navy's submarine onslaught on Japan. Displacement: 1,526 tons (surfaced). Armament: Ten 21-in torpedo-tubes (6 forward, 4 aft); 14 reloads; one 3-in gun. Speed: 20¼ knots (surfaced) 8¾ knots (submerged)
The same programme saw the commencement of 9 "medium" 600-tonners of the KS Type, a strange decision in view of the distances involved in the Pacific, but under the 1941 Emergency War Programme there was an immediate return to giant aircraft-carrying submarines with the 140 and 146 Classes. The 112 was a repeat of the 1937 A1 Type, a long-range cruising submarine intended to act as the headquarters for hunting groups of smaller submarines. The surface displacement was nearly 3,000 tons, and aircraft were carried, but most of the additional displacement was used to increase - to as much as 22,000 miles the 112.
These submarines were meant to play, their part in a grandiose plan to seek out and ambush American surface forces across the wide expanse of the Pacific, and they were supplemented by midgets to attack the enemy if he should refuse to leave his defended harbours. The aerial attack on Pearl Harbour was intended to be supported by a torpedo attack from some Type A midgets, and one of the minor mysteries of that debacle is how the Americans sighted and sank one of them at the entrance to Pearl Harbour before the main attack without alerting the defenses. The attack was not a success, nor was a similar attack on Sydney Harbour in 1912, but in the same year the British battleship Ramillies was badly damaged by a midget launched from a parent submarine off Madagascar.
The nation that introduced the Kamikaze concept had little difficulty in applying it to naval warfare, and in l943 the first of a range of suicide craft was developed, the Kairyu; it was a development of the Type A midget, but production did not start until early in 1945. A much better-known development was the Kaiten, basically a piloted version of the famous 24-in Type 93 "Long Lance" torpedo. The three later models of Kaiten used a high-speed hydrogen-peroxide engine, but suffered so many production problems that the Model 4 was fitted with a conventional torpedo motor and carried a much heavier warhead in compensation.
The main problem for the Japanese at the beginning of the war was not one of design, but the question of how they intended to use their submarines. From the start the long-cherished aim of a general fleet action was paramount in the Imperial Japanese
Navy's plans, and all submarine tactics had to be subordinated to that idea. Too much attention was paid to the need to maintain an offensive and aggressive outlook, which led to the grave error of assuming that warships were the only important targets for submarines. It also led to the equally serious error of neglecting the defense of merchant ships on the grounds that convoying was merely a defensive measure.
The lessons were painfully learned by the Japanese as American submarines proceeded to cut their lines of communication.
Losses of vital tonnage went up, so that it became harder and harder to reinforce the perimeter of island bases, which were essential to the Japanese maritime strategy. Worse, the homeland depended on imports for 20 per cent of the food consumed, 24 per cent of its coal, 88 per cent of all iron ore, and 90 per cent of its oil.
In the light of these statistics it is hard to understand why the Imperial Navy did not complete any escort vessels until 1940. Apart from a handful of old destroyers converted, the only further effort made by 1941 was the construction of another 22 escorts, and even they were given a low priority. The Japanese High Command did not expect the American submarines would be able to penetrate the defensive perimeter, and it was not until late in 1943 that any sort of convoy system was introduced. Even then, it was a very reluctant gesture and it was hampered by the desperate shortage of escorts. Over 4 million tons of shipping was sunk by American submarines, and by mines laid by submarines and aircraft, and when the war ended in August 1945 the Japanese mercantile marine comprised only 231 ships - in 1939 Lloyd's Register listed 2,337 ships!
The American submarines in the Pacific were supported by a small number of British and Dutch submarines, and after the collapse of Italy in 1943 the British were able to transfer reinforcements from the Mediterranean. By early 1944 there were three flotillas in the Far East, two at Trincomalee and a third at Fremantle in Australia, operating under American command. Because of their smaller size the British and Dutch boats were principally employed about the 10-fathom line west of Singapore where the big US submarines found it difficult to operate.