Mine Warfare Introductions
In many respects, international trade is the lifeblood of Japan's economy. Imports and exports totaling the equivalent of nearly US$522 billion in 1990 meant that Japan was the world's third largest trading nation after the United States and the Federal Republic of Germany (West Germany). Because of Japan's lack of raw materials, its exports have consisted almost exclusively of manufactured goods, and raw materials have represented a large share of its imports. The country's sense of dependency and vulnerability has also been strong because of its lack of raw materials.
In 1986 the Japanese merchant fleet included 10,011 ships with a total displacement of 38.5 million gross tons, a steady decrease from 10,425 ships with a total gross tonnage of 40.4 million in 1984. Of the nearly 1,200 Japanese ships of 1,000 gross registered tons and over, there were more than 300 bulk carriers; more than 250 petroleum, oils, and lubricants tankers; some 240 vehicle and cargo carriers; and more than 150 refrigerated cargo ships. The remainder were passenger and passenger-cargo ships, container ships, roll-on/roll-off cargo ships, chemical tankers, combination ore and oil carriers, and other specialized types of large ships. By the year 2005, Japan had 2,059 ships of 1,000 gross registered tons and over, with a total displacement of 135 million gross tons. This was second in the world only to Greece, which had 2,426 ships with a total displacement of 158.5 million gross tons.
Japan has very limited domestic oil reserves and relies almost totally on imports to meet its consumption needs. As of January 2006, Oil & Gas Journal (OGJ) estimated that Japan held 59 million barrels of proven oil reserves. During the first three quarters of 2006, Japan produced about 125,000 barrels per day (bbl/d) of oil, of which less than five percent was crude oil. The vast majority (83 percent) of Japan's oil production comes in the form of refinery gain, resulting from the country's large petroleum refining sector. For 2006, EIA forecast that Japan would consume 5.3 million barrels per day (Mmbbl/d) of oil. Japan remains the second largest net importer of oil behind the United States and the third largest consumer of oil behind the United States and China.
Sea mines -- explosive underwater devices that damaged, sank, or deterred ships -- were weapons that had difficulty gaining the same acceptance as guns, bombs, and torpedoes. In the American Civil War, the Russo-Japanese War, and World War I, mines sank or damaged more ships than gunfire or torpedoes. The greatest number of these mines had been used in "defensive" fields -- that is, within friendly waters to safeguard a port or coastal route, while "offensive" mining occurred in enemy controlled waters.
Early in World War II, American planners recognized Japan?s reliance on shipping and its vulnerability to blockade. The U.S. Navy's objectives for mining Japan's "outer zone" were broad and simply a statement of offensive mining's potential. Those objectives were: "To disorganize the enemy maritime supply system, deny him safe ports and shipping routes for the transport of essential war and economic materials, to sink and damage as many of his ships as he would expose to mine risk, and to impose upon him the military and economic burden incident to the establishment and maintenance of a mine defense."
In August 1942 the Mine Warfare Operational Research Group in the Navy Department recognized Japan?s serious vulnerability to attacks on shipping and recommended American submarines begin an "'attrition mining" campaign in Japanese controlled waters.12 The first such mining occurred on October 16th. Japan laid defensive minefields to keep U.S. submarines from entering and mining the Sea of Japan.
Though slow to start, aerial minelaying in Japan's "Outer Zone" by the air forces of Britain, Australia, and the United States accomplished a worthwhile attrition of Japanese shipping. In March 1945, U.S. B-29 bombers leapt this barrier. Allied aircraft dropped more than 12,000 mines during Operation Starvation - the code name for mining the waters in and around the islands of Japan. These mines carried 1120 pounds of TNT each and by the time Japan surrendered in 1945, airdropped offensive mines had done extensive damage to Japanese shipping.
Throughout the war, the Japanese were unprepared to counter the mine threat. Despite the dispersed nature of the "outer zone" campaign, they were frequently surprised due to Allied success in keeping the missions secret and also from their own failure to communicate between commands. Their handicaps in minesweeping amplified the effect of relatively small Allied efforts that used unsophisticated magnetic and acoustic mines. They also suffered from a lack of cooperation between scientists and the military, but nonetheless devised methods to sweep all varieties of mines except the new low-frequency acoustic and the pressure types.
By war's end the Japanese had 20,000 men and 349 ships devoted to defense against the mining campaign.
