The Advent of Submarine Warfare. The epoch for Submarine Warfare, for all intents and purposes, opened with the brusque plume of an exploding torpedo launched by a German U-boat sinking SS LUSITANIA, a British passenger liner, off the southwest coast of Ireland on May 7, 1915, leaving 1154 dead, including 114 Americans. Patently, the submarine evolved from a very awkward beginning into a very versatile, very stealthy, and very cost-effective warship. The following Benefit-to-Cost, B/C, analyses compare the costs of ships sank by warships to the costs of those warships lost in the effort. Statistically, this B/C portrays the efficacy of the submarine warship as a very cost-effective, ship-sinking interdictor of ocean sea-lanes. In WW-I, German U-boats sank 5,708 merchant ships, and 62 warships. To absorb the magnitude of those numbers, you may have to read them twice-over so as not to trivialize their significance—or, their economic significance. These sinking numbers equate to some 11,018,865 dead-weight tons (dwt) of steel in merchant-ship hulls plus their consigned cargo, and 538,535 dwt of warships. Figuratively, and literally, that’s a colossal “sunk cost.” This sunk cost can be estimated parametrically to be $39.4-billion—at the time-value of money for 1918. Then, dividing that “Benefit” by the “Cost” of the lost of 178 U-boats estimated parametrically to be $1.3-billion, yields a B/C ratio of 30.5! Notably, a B/C of 1.0 is breakeven, doubling your money is 2.0, and 4.0 is considered a beneficial venture. There was a lot to be learned in the two intervening decades between WW-I and WW-II. Ardent studies of the technologies and techniques associated with Anti-Submarine Warfare (ASW) were lessons that had to be learned by the “Hunter,” and the “Hunted.” Inevitably, as if portended by the foreboding Winds of War, German U-boats in WW-II sank 23.4-million dwt of allied shipping plus their cargo, which together is estimated to be $78.5-billion. Dividing that by the lost of 781 U-boats estimated to be $5.7-billion yields a B/C of 13.8. In comparison to the greater B/C ratio in WW-I, one deduces that ASW in the Atlantic apparently helped to cut this telltale ratio by more than half. I doubt though that this lesser B/C was any solace to those having to stomach the lost of $78.5-billion– at the time-value of money for 1945. Meanwhile, On the Far Side, how did US submarines fare in WW-II against the Eastern island empire of Japan in the Pacific? US submarines sank 4.9-million dwt of Japanese warships, and merchant ships plus their cargo, which together is estimated to be $16.3-billion. Dividing that Benefit by the Cost of the lost of 52 US submarines materially estimated to be $355.3-million yields a B/C of 45.9! At the beginning of 1943, as another statistical example, over the sea-lane between Taiwan and the Philippines at the Bashi Channel choke-point for the Luzon Straits connecting the South China Sea with the Philippine Sea, Japanese oil-tankers were transporting some 1.5-million barrels of crude oil per month for Japan’s refineries to make distillate fuels for their war-machines. That sea-lane was interdicted by US submarines, literally torpedoing Japan’s oil-imports. By the end of 1944, this crude-oil supply had been reduced by 80 percent to something less than 300,000 barrels per month. US submarines, with only 2% of all US Navy personnel, were credited with sinking 55% of all Japanese merchant ships, and 29% of all Japanese warships. This era of submarine warfare, however, is still a “work-in-progress.” It began auspiciously on May 7, 1915, when a German U-boat torpedoed and sank SS LUSITANIA off the southwest coast of Ireland. For the moment, its log’s tab is set on May 21, 1982, when a British nuclear-powered attack submarine, HMS CONQUEROR, torpedoed and sank Argentina’s battle cruiser BELGRADO off the Argentine coast in the approaches to the Falkland Islands—a 150-year-old British colony that occupying Argentine armed forces two weeks later surrendered back to British armed forces on June 4, 1982. The lead-in photo for this closing is a subtle depiction of the forebodingness of Submarine Warfare for several significant reasons. It could be said to be a chilling photo because it is of a submarine warship entering a German port. In 1936, Chancellor Adolf Hitler officially opened the Kiel Canal, and relegated the inaugural passage to one of Der Kriegsmarine Unterseebooten. So, the Third Reich’s construction of the Kiel Canal may have been for other means to bolster Germany’s maritime economy.Thus, HARDER’s transit of the Kiel Canal at the end of Kieler Woche could be deemed to have been some surrealistic scheme to top-off the Kiel Canal’s twenty-fifth anniversary with a transit of a Type XXI U-boat. But perhaps, I just consider this photo to be significant because I am the young submarine officer pictured on deck with the Anchor Detail as HARDER stood in to Kiel that day. Nevertheless, it remains: Submarines Sink Ships!
 Notably, in 1916, the year after a U-boat sank SS LUISITANIA, USS E-1 (SS 24), which was 135 feet in length with a submerged displacement of about 400 dwt, became the first submarine to cross the Atlantic under her own power, that is, the first trans-Atlantic crossing by a coal-oil-powered submarine.
 Notably, this B/C was higher than that for German U-boats because by my deductive reasoning the US tactics of submarine approach and attack were with more stealth, and that ASW by the Japanese Navy was less intense and less effective. Read previous posts by Captain Wellborn here https://aticourses.com/blog/index.php/2011/07/08/the-efficacy-of-submarine-warfare/ https://aticourses.com/blog/index.php/2011/07/11/the-evolution-of-a-submarine-as-a-warship/