Post 8, the only access to the ground zero area from the Base Camp,
ensured that no unauthorized individuals entered the area (9; 12).

At 0100 hours on 16 July, military policemen from Guard Posts 3, 5, 6,
and 7 met to compare their logs of personnel authorized to be in the
ground zero area. The guards then traveled along the access roads to
clear out all project personnel. As individuals left for their
assigned shelters or stations, their departures from the test area
were recorded in the military police logs. By 0200 the area sweep was
completed, and the military police went to their shelters and
stations. A final check of personnel was made in each shelter (3; 9;
12).

At the time of detonation, 99 project personnel were in the three
shelters: 29 in the north shelter, 37 in the west shelter, and 33 in
the south shelter. Dr. Oppenheimer, Dr. Bainbridge, and other key
personnel awaited the firing at the south shelter, which served as the
Control Point. Figure 2-3 shows the exterior of the south shelter;
figure 2-4 gives an interior view of one of the shelters, most likely
the south. Although most of the shelter occupants were civilians, at
least 23 military participants were spread among the three shelters
(1; 12).

The remainder of the test site personnel were positioned at the Base
Camp 16 kilometers south-southwest of ground zero, or on Compania
Hill, or at the guard posts. Important Government officials, such as
General Groves and Dr. Vannevar Bush, Director of the U.S. Office of
Scientific Research and Development, viewed the detonation from a
trench at the Base Camp. The Base Camp is depicted in figure 2-5.

The military police of Guard Posts 1 and 2 were instructed to be in
foxholes approximately five kilometers west and north, respectively,
from their posts. The military police of Guard Posts 3 and 4 were
instructed to be in foxholes south of Mockingbird Gap. A radiological
safety monitor was assigned to the group from Guard Post 4. Guard Post
5 personnel were to be in the south shelter, Guard Post 6 personnel in
the west shelter, and Guard Post 7 personnel in the north shelter.
The military police of Guard Post 8 remained at that post, 400 meters
east of the Base Camp (9).

An evacuation detachment of between 144 and 160 officers and enlisted
men was stationed near Guard Post 2, about 14 kilometers northwest of
ground zero. These men were on standby in case ranches and towns
beyond the test