Nuclear Weapons Tests in the Pacific

Hartley O. Holte

By 1958, several nuclear weapons “tests” had already been conducted by the US in such well known locations as: Alamogordo, Hiroshima, Nagasaki, Nevada, and Bikini. With the advent of several other nation’s interests in developing their own nuclear weapons capability, the US felt that continued design of special weapons for a number of different delivery systems would greatly enhance our capability to remain as the post-WWII military superpower. Accordingly, as we designed and produced many new weapons types, designs, sizes, etc., yet another series of tests were required to assess workability, capability and effects. Such a series of tests were planned to be conducted in the spring and summer of 1958, again in the Bikini Atoll area of the Marshall Islands. This test series was given the name, “Operation Hardtack”.

Three members of the USNA Class of 1955 were known to be directly involved in disparate aspects of this test series. First, the carrier, USS Boxer (CVA 21) was assigned to transport the test weapons and support materials from the US mainland to the islands. Geoff Gardner was the ship’s gunnery officer and was directly responsible for the weapons while on board. Secondly, the Sumner class destroyer, USS Mansfield (DD 728), flagship of DESRON 9, was detached from the squadron and deployed independently to the Bikini/Eniwetok/Kwajelein area to provide additional naval support. Hartley Holte (Geoff’s 13th Company “wife” at USNA) was Operations Officer for Mansfield, responsible for planning, communications and security for its variety of roles. Thirdly, Dave Trapp was an Air Force B-57 aviator with the detachment assigned to airborne monitoring of effects during the tests.

Boxer remained anchored in Bikini lagoon long enough to offload test weapons and for Geoff and Hartley to get together briefly on Boxer. Boxer then remained in the area to serve as a command platform for many tests. Geoff’s writings in his booklet, “The Captain Has the Conn”, describes well his experiences at Hardtack which mirror many of mine on our destroyer. We were not aware of Tripp’s presence or involvement until many years later, but knew that his unit had been instrumented for radiation, temperature and camera work, and flew directly through the “mushrooms”.

Mansfield assumed four specific roles:

1. Act as weather observation platform for monitoring wind patterns up to and over 100,000 feet, using radiosonde chaff-filled balloons launched off the fantail of our ship by our embarked three-man enlisted weather team. We tracked, by radar, each balloon and reported observations prior to and during each test.
2. Act as emergency evacuation ship for local natives (and perhaps, US test and support personnel?), in case a change of wind direction might place the populace in jeopardy. Fortunately, there was no need for this “service” by our ship.
3. Act as a “plane guard” for aircraft take-offs and landings at Kwajelein. This was a role akin to that which destroyer sailors routinely performed for carriers at sea (before the wide-spread use of helos). We were there, but, again, there were no incidents requiring our assistance.
4. Act as a test ship (read guinea pig) for one of the test detonations! We were given a specific anchorage location, 5,000 yards from “ground zero” for this underwater “shot”, and were told that the scientists predicted that the resulting water plume would speed outward and dissipate at about 3,500 yards. We were instrumented at several locations on the ship for radiation, temperature and shock. We were also provided with a radar scope camera, bolted to one of our “repeaters” in Combat Information Center (CIC) where we could “observe” the radar image of the blast. As the shot was initiated, the resultant shock wave knocked the 25 pound camera off the pedestal---and it landed on deck about two inches from my foot. We experienced two shock waves, first directly though the water and immediately after as the shock bounced off the lagoon bottom. At least, the water plume did, indeed, die out at 3,500 yards!

The whole Hardtack operation was highly classified at the time and I was tasked to sequester all personal cameras. (Of note is that there has now been a great deal of film and written material about Hardtack made available to the public.) We witnessed some 30 different shots over our two months there, from the relatively small underwater test to which we were subjected, up to the multi-megaton monsters for which we were stationed many miles away at sea. .Mansfield was told later that we were the ONLY active duty, manned ship ever subjected to an atomic weapons test!

There were some enjoyable aspects of our cruise; beer fests and softball games on one of the Bikini Atoll islands set aside for recreation; a ship’s officer versus enlisted basketball game during a briefing at Kwajelein; learning to skin dive/snorkel for two hours in Bikini Island shallow waters (4-10 feet depth) amidst the beautiful fish and coral formations (no sharks!); and our Exec bringing back a huge conch shell from a separate skin-diving adventure.

Our deployment was to have been only for three months, but we were extended for another two months to serve with 7th fleet out of the Pescadores Islands to support the Chinese Nationalists during the Quemoy/Matsu “Formosa Crisis”---but as they say, that is another story.