At the start of WW2 Japan had amassed the biggest Carrier Fleet of any of the Combatant Nations. She could boast 6 Large & 4 Smaller Carriers with more on the drawing board. However it would be the Battle of Midway in Late May & Early June 1942 that would spell the end of Japan's dominance in this area. The Americans had broken the Japanese Naval Code (JN 25) before the Pearl Harbor attack in December 1941 and were reading most of the messages being sent back & forth. This led to an intelligence coup when a Code Breaker came up with an ingenious method of confirming that Midway was Japan's next target. Admial Isoroku Yamamoto (Commander in Chief of the Japanese Imperial Fleet) wanted to lure the US Navy in to a trap at Midway so that he could destroy their Aircaraft Carriers and buy more time for the Japanese to consolidate their newly conquered territories. Unbeknown to him of course the Americans were now one step ahead and knew that an attack was coming but weren't sure exactly where although they were almost certain it would be Midway. The Japanese kept referring to the Attack's objective as "AF". So the American Code Breaker suggested sending a false message that Midway was short of drinking water that they knew the Japanese were sure to pick up. Sure enough as soon as the false message was sent they read the Japanese Coded response that "AF" was short of drinking water so confirming that Midway was indeed the target. Forewarned they sent a 3 Carrier Task Force to the North East of Midway in Late May 1942 to await the Japanese attack. At first unable to locate the Japanese Task Force they were finally spotted by a PBY Catalina Flying Boat heading for Midway and the US Navy Task Force prepared for battle. At this stage of the War the standard US Navy Torpedo Bomber was the obsolete Douglas Devastator and a lot of these were lost in the 1st wave but screaming down from 10,000 feet were the USS Yorktown's Douglas Dauntless Dive Bombers and they made the Japanese pay a heavy toll as 1000 lb bombs tore in to the Hiryu, Soryu, Akagi & Kaga all of which participated in the Pearl Harbor Attack just 6 months earlier. All 4 Japanese Carriers were lost with only the USS Yorktown sunk on the American side. This proved to be the turning point in the Pacific as Japan would never again be able to launch a large scale attack with Aircraft Carriers and the initiative had been well & truely snatched back by the Americans.