The 1399 Engineer Construction Battalion was an all Japanese American military unit stationed in Hawaii during World War II. Activated on April 26, 1944, at Schofield Barracks, Hawaii, the unit constructed vital military defense installations, including a half-million-gallon water tank, jungle-training villages, artillery emplacements, ammunition storage pits, water systems, warehouses, a Flying Fortress airfield, auxiliary roads, and rest camps.