Three months later, on 7 August 1942, 11,000 United States Marines landed on Guadalcanal, and 3,000 U.S. Marines landed on Tulagi and nearby islands. The Japanese troops on Tulagi and nearby islands were outnumbered and killed almost to the last man in the Battle of Tulagi and Gavutu–Tanambogo and the U.S. Marines on Guadalcanal captured an airfield under construction by the Japanese. Thus began the Guadalcanal and Solomon Islands campaigns that resulted in a series of attritional, combined-arms battles between Allied and Japanese forces over the next year which, in tandem with the New Guinea campaign, eventually neutralized Japanese defenses in the South Pacific, inflicted irreparable losses on the Japanese military—especially its navy—and contributed significantly to the Allies' eventual victory over Japan.