Atomic Bomb engineering was carried out by the Z Division, named for its director, Dr. Jerrold R. Zacharias from Los Alamos. Z Division was conceived as an ordnance design, testing, and assembly arm. However, space was at a premium at Los Alamos. Additionally, members of Z Division needed to work closely with the military. Groves also decided as part of an effort to retain personnel to focus the laboratory more on weapons development by relocating various weapons production and assembly activities away from Los Alamos. Thus, the decision was taken to move Z Division to the old Oxnard Field. Already at the close of the war, the engineering group of Z Division had begun consolidating weapons assembly functions there. Z Division was initially located at Wendover Field, Utah but moved to Oxnard Field, New Mexico, in September 1945 to be closer to Los Alamos. By 1946, the site was being referred to as "Sandia Base" after the nearby Sandia Mountains.