Vintage Armed Forces Radio Service Kentucky Day in the Marianas Black and White Photograph 9" x 7". In June 1944, Admiral Raymond A. Spruance's 500-ship fleet, carrying about 125,000 Marines and Sailors steamed 1,000 miles from the Western Marshall Islands to the South Mariana Islands. This fleet included most of the Navy's carriers and battleships, along with many of its transports of the Pacific Fleet. The Mariana Islands were the last bastion of Japan's Central Pacific perimeter. Their capture by American Forces severed the Japanese supply lines with the Caroline Islands territories further south and pushed the defense west to the Philippines while opening the Japanese homelands for aerial assaults. Spruance's Task Force 58 launched the first of many pre-invasion air sorties on June 11 on Japanese positions, airplanes, and ships. Both fast and escort carriers participated in these attacks that lasted until the capture of Guam on August 10.