Appendices - Hirohito's War
APPENDIX A: SUBMARINES - THE UNDERSEA WAR
US Submarine Achievements in the Pacific War: Within six months of his taking command of submarine operations in the Pacific War, Lockwood’s forces’ record of performance took a dramatic upward turn. In the first three months of 1943 US submarines sank 57 Japanese merchantmen. By the last quarter of the year the tally had risen to 106, accounting for 65 percent of Japanese merchant ships sunk in that period. In the following quarter, January to March 1944 US submarines sank 136 merchant ships with an aggregate weight of 500,000 tons.
As well as improved torpedoes and operating procedures, Submarine Force, the US Pacific Fleet’s force, was the recipient of an increasing supply of new submarines: the Gato Class and its up-dated successor, the Balao Class. The 312ft by 27.3ft beamed Balao Class with up-rated thick steel and doubled-hull, had more powerful diesel engines and batteries that enabled it to carry out the long range, long duration missions required in the broad reaches of the Pacific Ocean. New submarines delivered increased from 39 in 1942 to 50 the following year and 80 in 1944.
USS Balao would later star as the pink submarine in the Blake Edwards comedy movie Operation Petticoat  with Cary Grant, Tony Curtis and Joan O’Brian, and Pacific submarines would feature in another post-war movie. In June 1945, Lockwood sent nine submarines into the Sea of Japan via the Straits of Tsushima supposedly to test the effectiveness of a new FM sonar in locating minefields. The Operation Barney expedition sank 28 boats (58,000 tons) but USS Bonefish was lost with all hands. It was later questioned whether the operation was justified. Some suspected that it was a revenge mission for Lockwood’s favorite commander ‘Mush’ Morton while others have argued it was a statement of intent to the Russians that the US intended to control the Sea of Japan after the war. However Lockwood may simply have wanted to kill merchant ships and to get across the message to Japanese leaders that nowhere was safe from the US Navy. Operation Barney would later feature as a movie, Hellcats of the Navy  starring future President Ronald Reagan and his wife Nancy Davis (her screen name). It was the only movie they made together.
A record monthly submarine tally of 68 ships was achieved in October 1944, a month in which 130 Japan merchant vessels were lost. Adding to the ravages of submarines, Nimitz’s patrolling fleet task forces in the South China Sea, combined with the Army Air Force now based in the Philippines, were increasingly joining in the wholesale destruction of the Japanese Merchant Fleet. By the first quarter of 1945 US submarine kills on merchantmen, 60 in total, had fallen back to the levels of the first quarter of 1943. Noticeably in this quarter US submarine tallies represented less than 30 percent of Japanese vessels sunk; as the US surface fleet began to surround Japan, it increasingly began to interdict Japanese coastal traffic as well as merchant ships making the short crossing of the Sea of Japan from Korea. The mining of the key straits guarding the Inland Sea and the Kanmon Straits between Kyushu and Honshu, further added to the misery of Japanese marine traffic. In aggregate, in the course of the Pacific War, US submarines sank 4.8m tons of merchant shipping representing 55 percent of their total losses. Having started the war with 6m tons of shipping, and in spite of building 3.25m tons, Japan ended the war with less than 2m tons of which only 312,000 tons was considered to be still serviceable. Unarguably Lockwood’s Submarine Force was the major single contributor to the economic strangulation of Japan.
For the loss of 52 submarines and 348 officers and 3,136 crewmen killed, the US submarine force probably represented the best return on investment of any service in the Pacific War. An aggregate of 1,392 Japanese naval and civilian ships were sunk achieving an average rate of 0.8 kills per submarine patrol. US submarines were perhaps fortunate that Japan was slow to develop destroyer protected convoy systems; as was typical of much of Japan’s planning, defense systems and technology were largely sacrificed to offensive weaponry.
Albeit smaller than their Japanese counterparts, US submarines’ hulls were better designed and more capable of withstanding depth charges. In this respect, they were also helped by the fact that Japanese depth charges carried relatively light charges; Type-95 was standard at the time war broke out, with a 100kg charge of Type-88 explosive, (ammonium perchlorate and ferro silicate). Also, at least in the early part of the war, Japanese depth charges tended to be set too shallow as the Type-95 had just two settings at 100ft and 200ft compared to the standard diving depth achievable by US submarines which was usually 300ft. Lockwood’s Submarine Force was helped by the fact that Japanese destroyers in the pre-war period had largely been designed as fleet attack weapons rather than defensive anti-submarine weapons.