30 RADIOLOGICAL CLEANUP OF ENEWETAK ATOLL When that war was concluded, Japan, having been on the side of the victorious Allies, was awardedthe islands lying north of the equator by the Treaty of Versailles. This was in the form of a mandate to control and develop these islands, but not to fortify them. The Japanese established the South Seas Bureau with headquarters ar Kolonia in Ponape, and divided the mandated territory into six districts. one of which was the Marshall Islands. Visits to Enewetak were made by the Japanese Navy and by Japanese traders. Both Enewetak and Ujelang were administered from Ponape, and the only foreign residents on Enewetak were a Japanese trader and his two assistants. A weather Station was established there in the 1930’s, but other Japanese associations with the atoll languished. Early in World WarII, the Japanese set out, contrary to the terms of the mandate, to make Enewetak Atoll a strategic base in their planned conquestof the Pacific. Japan maintained a guard unit of about 20 men on Enjebi until December 1942, when construction workers arrived to construct an airstrip. This was completed in July 1943, and, in October, the detachment at Kwajalein was moved to Enjebi to act as a maintenance force. In January 1944, [10 aviation officers and men were billeted on Enjebi, and 2,686 soldiers were landed on Enewetak to prepare the defense on the atoll. These were placed on Enjebi, Medren, and Enewetak. About 1,000 laborers and other noncombatant personnel were also present. The aviation personnel were to be evacuated to Truk by flying boat but, for most of them, this operation was begun toolate.42 Noting the preparations for battle, the 30 dri-Enewetak inhabitants of Enjebi moved to islands on the eastern reef. BATTLE OF ENEWETAK: FEBRUARY 1944 Theoriginal U.S plan for invading the Marshalls included amphibious assaults on strongly defended atolls of the Ratak or eastern chain in order to secureairstrips there. Air reconnaissance in December 1943 showed the construction of a Japanese airstrip on Kwajalein Island, so plans were altered to bypass Wotje, Maloelap, and Mili on the Ratak Atolls, and to attack the north and south ends of Kwajalein Atoll simultaneously. Planning included the capture of Majuro Atoll which was very lightly defended. After securing Kwajalein, Enewetak was to be attacked. The Marshall Islands operation was code-named ‘‘Flintlock’’ and was under the overall command of Vice Admiral Raymond A. Spruance. The capture of Enewetak was considered to be a preliminary step to landing on Truk farther west and was code-named‘‘Catchpole.’’ Manyof the lessons learned in the previously completed campaign to capture the Gilbert