Technically a Spanish colony, Enewetak was not known to Europeans until visited in 1794 by the British merchant sloop Walpole, who called it "Brown's Range" (thus the Japanese name "Brown Atoll"). It was visited by only a dozen or so ships before the establishment of the German colony of the Marshall Islands in 1885. Along with the rest of the Marshalls, Enewetak was captured by Japan in 1914 and mandated to them by the League of Nations in 1920.
The Japanese mostly ignored the atoll until World War II. In November 1942, they built an airfield on Engebi Island, which was used for staging planes to the Carolines and the rest of the Marshalls. When the Gilberts fell to the US, the Japanese Army's 1st Amphibious Brigade came in to defend the atoll, January 4, 1944. They were unable to finish fortifying the place before the February launch of Operation Catchpole by the US, which captured all the islets in a week.
After the war, the residents were evacuated, often involuntarily, and the atoll was used for atomic bomb testing. This went on from 1948 to 1962, when atmospheric testing ended. The first hydrogen bomb test, in 1952 was at Enewetak.