Operation Hailstone
Operation Hailstone was a large-scale United States Navy air and surface attack on Truk Lagoon on 17–18 February 1944, conducted as part of the American offensive drive against the Imperial Japanese Navy in the Pacific Ocean theatre of World War II. == Background == Japanese troops occupied Micronesia, including the Caroline Islands, in 1914 and established Truk as a base as early as 1939. The lagoon was first built up as an anchorage for the Imperial Japanese Navy's 4th Fleet, its "South Seas Force".