Outgunned at sea, the American strategy for victory required a holding action against the IJN until the much greater industrial potential of the U.S. could be mobilized to build a fleet capable of projecting American power to the enemy heartland. The Battle of Midway, together with the Guadalcanal campaign, marked the turning point in the Pacific. Between June 4–7, 1942, the United States Navy decisively defeated a Japanese naval force that had sought to lure the U.S. carrier fleet into a trap at Midway Atoll. The Japanese fleet lost four aircraft carriers to the U.S. Navy's one American carrier and a destroyer. After Midway, and the exhausting attrition of the Solomon Islands campaign, Japan's shipbuilding and pilot training programs were unable to keep pace in replacing their losses while the U.S. steadily increased its output in both areas. Military historian John Keegan called the Battle of Midway "the most stunning and decisive blow in the history of naval warfare." Guadalcanal, fought from August 1942 to February 1943, was the first major Allied offensive of the war in the Pacific Theater. This campaign saw American air, naval and ground forces augmented by Australian and New Zealander forces in a six-month campaign slowly overwhelm determined Japanese resistance. Guadalcanal was the key to controlling the Solomon Islands, which both sides saw as strategically essential. Both sides won some battles but both sides were overextended in terms of supply lines. The rival navies fought seven battles, with the two sides dividing the victories. They were: Battle of Savo Island, Battle of the Eastern Solomons, Battle of Cape Esperance, Battle of the Santa Cruz Islands, Naval Battle of Guadalcanal, Battle of Tassafaronga and Battle of Rennell Island. Each of the sides pulled out its aircraft carriers, as they were too vulnerable to land-based aviation. In preparation of the recapture of the Philippines, the Allies started the Gilbert and Marshall Islands campaign to retake those islands from the Japanese in summer 1943. Enormous effort went into recruiting and training sailors and Marines, and building warships, warplanes and support ships in preparation for a thrust across the Pacific, and to support Army operations in the Southwest Pacific, as well as in Europe and North Africa. The Navy continued its long movement west across the Pacific, seizing one island base after another. Not every Japanese stronghold had to be captured; some, like the big bases at Truk, Rabaul and Formosa were neutralized by air attack and then simply leapfrogged.