Part 1 of a film describing the testing and use of the first 5 atomic bombs. There was one test (the Trinity test), then two bombs used over Japan, and the two tests at Bikini Atoll. This film documentary was most likely used to brief Congress in order to get funding for further development and testing of nuclear weapons.

Operation Hardtack Underwater Tests 1958. Part 3 of 4. Underwater nuclear tests, testing kill mechanisms for use against submarines and surface ships. The deep water Crossroads shot Charlie had been cancelled after the test fleet was rendered unusable (by the ships being covered by highly radioactive contamination, which was unexpected) in the 1946 Baker shot. A deep water shot had been carried out in May 1955 off the coast of California (the Wigwam shot), but weather conditions had disturbed the test array. The primary purpose of the Wigwam shot was testing submarine hull damage. The Hardtack shots Wahoo and Umbrella were carried out at Enewetok Atoll in the Pacific. The Wahoo shot was done in deep water to study surface ship hull damage in deep water nuclear explosions, and the Umbrella shot was done in shallow water to get more data in shallow water detonations. During the Wahoo test, a manned submarine (USS Bonita SSK-3) was submerged near the blast, and experienced severe shock, but no damage to the submarine hull was experienced. A photographer on a nearby island witnessed a tsunami wave that covered the island. The use of shipboard washdown systems was tested as a means of reducing contamination from the radioactive base surge. Hull damage on the surface ships was light, but some ships experienced machinery damage in the engine room.