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The ''Lexington''-class aircraft carriers were a pair of aircraft carriers built for the United States Navy (USN) during the 1920s. The ships were built on hulls originally laid down as battlecruisers after World War I, but under the Washington Naval Treaty of 1922, all U.S. battleship and battlecruiser construction was cancelled. The Treaty, however, allowed two of the unfinished ships to be converted to carriers. They were the first operational aircraft carriers in the USN and were used to develop carrier aviation tactics and procedures before World War II in a series of annual exercises. They proved extremely successful as carriers and experience with the ''Lexington'' class convinced the Navy of the value of large carriers. They were the largest aircraft carriers in the USN until the s were completed beginning in 1945. The ships served in World War II, seeing action in many battles. Although ''Lexington'' was sunk in the first carrier battle in history (the Battle of the Coral Sea) in 1942, ''Saratoga'' served throughout the war, despite being torpedoed twice, notably participating in the Battle of the Eastern Solomons in mid-1942 where her aircraft sank the Japanese light carrier . She supported Allied operations in the Indian Ocean and South West Pacific Areas until she became a training ship at the end of 1943. ''Saratoga'' returned to combat to protect American forces during the Battle of Iwo Jima in early 1945, but was badly damaged by kamikazes. The continued growth in the size and weight of carrier aircraft made her obsolete by the end of the war. In mid-1946, the ship was sunk during nuclear weapon tests in Operation Crossroads. ==Development== The ''Lexington''-class was originally designed as battlecruisers, with heavy guns, high speed, and moderate armor protection. The Navy laid down six ships of the class in 1919–20. When the battlecruisers were cancelled under the Washington Naval Treaty of 1922, two of the unfinished ships were designated for completion as carriers. ''Lexington'' and ''Saratoga'' were selected since they were the most advanced of the six ships in construction.〔Stern, pp. 27–30〕 Conversion became a series of compromises and mixed blessings which would not have arisen had they been "specifically designed carriers" from the outset. On the plus side, the ships would have better anti-torpedo protection, larger magazines for aircraft bombs and, with the after elevator higher than otherwise, more room for aircraft landings. On the minus side, a converted battlecruiser would be slower than a specifically designed carrier, have 16 percent less hangar space, less emergency fuel and, with "narrower lines" aft, not as wide a runway for which to aim. Costs were similar. A brand-new aircraft carrier was estimated at $27.1 million. Conversion of a ''Lexington'' class was $22.4 million, not counting the $6.7 million already sunk into them. Added together, the figure rose to $28.1 million.〔Friedman, p. 43〕〔Both of these figures (the $6.7 and $22.4) are estimates for one of the lesser-advanced ships like ''Ranger''. The former cost would be higher and the second lower for one of the more-advanced ships.〕 The bottom line, with the signing of the treaty, was that any capital ships under construction by the five signatories (the United States, Great Britain, France, Italy and Japan) had to be canceled and scrapped. For battlecruisers, this encompassed the United States ''Lexington'' class, Japan's , and Great Britain's G3 battlecruisers.〔See: Washington Naval Treaty, Chapter II, Part III, Section II〕 For the U.S. Navy, the choice seemed clear. If it scrapped all six ''Lexington''s in accordance with the treaty, it would throw away $13.4 million that could otherwise go toward aircraft carriers. The Navy opted for the latter course.〔 The next challenge the Navy's Bureau of Construction and Repair faced was the tonnage cap set by the treaty. Carriers were to be no more than 27,000 tons. An exception, spearheaded by Assistant Secretary of the Navy Theodore Roosevelt Jr. and added to the treaty, allowed capital ships under conversion to go up to 33,000 tons, an increase of 6000 tons.〔〔See: Washington Naval Treaty, Chapter I, Article IX〕 This would almost not be enough for a conversion without removing half the power plant, something the Navy General Board did not consider an option. Creative interpreting of a clause in the treaty allowed a potential way out of this situation.〔 The clause (Chapter II, Part III, Section I, (d)) read: Without this clause, conversion might not have been feasible. Estimates made in 1928 estimates for the two ships put ''Lexington'' at an actual tonnage of 35,689 tons and ''Saratoga'' at 35,544. On official lists, the number given was 33,000 tons, with the footnote, "(number ) does not include weight allowance under Ch. 11, pt. 3, Sec. 1, art. (d) of Washington Treaty for providing means against air and submarine attack". This tonnage was used by these ships for their entire careers.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Lexington-class aircraft carrier」の詳細全文を読む スポンサード リンク
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