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On August 7, 1942, the U.S. 1st Marine Division begins Operation Watchtower, the first U.S. offensive of the war, by landing on Guadalcanal, one of the Solomon Islands.
Weeks earlier, the Japanese landed on Guadalcanal Island and began constructing an airfield there. Operation Watchtower was the codename for the U.S. plan to invade Guadalcanal and the surrounding islands. During the attack, American troops landed on five islands within the Solomon chain. Although the invasion came as a complete surprise to the Japanese (bad weather had grounded their scouting aircraft), the landings on Florida, Tulagi, Gavutu and Tananbogo met much initial opposition from the Japanese defenders.