CASTLE Bravo was the first in a series of nuclear tests conducted by the United States Military in the Marshall Islands in March 1954. The first of these tests was called “Bravo”, and was by far the most destructive, and remains to this day as the worst radiological disaster that the United States has ever caused. Bravo wasn’t quite the first hydrogen, or thermonuclear, detonation, but it was by far the most destructive to that point, having an estimated yield of 15 megatons of TNT. That’s 15,000,000 tons.1 The amount of raw power that was unleashed that day would be equivalent to creating your own star. What made CASTLE Bravo so destructive can be ascribed a few different factors: fallout, the “tritium bonus”, and nuclear tensions.
When a nuclear detonation happens, the residual debris and any leftover material from the fuel that isn’t annihilated by the explosion becomes intensely radioactive and pulverized into a powdery form that can almost be mistaken for snow under some circumstances. This is what happened with the case of both the islanders living on the atolls near the test site as well as with the Japanese fishing vessel Lucky Dragon No. 5 or “Daigo Fukuryu Maru”. The sailors on board were within the vicinity of the explosion when it happened and had an “ash of death” rain down upon them.2 This “ash of death” was the pulverized remains of coral reefs that had been jettisoned and ionized in the air and rained back down as powdery “snow” and “ash”. All of the sailors on board suffered acute radiation sickness, and they were the avenue for the rest of the world learning about what happened on Bikini Atoll that fateful day. The islanders themselves also encountered this very same ash raining down back on them, but were not evacuated from the quickly deteriorating conditions until days later.3 The weather patterns of the day were scheduled to have blown the fallout into an uninhabited area of the Pacific Ocean, but the wind changed at the last moment and blew it all over the Marshallese, ruining several islands to this day.
The Bravo detonation itself was 15 megatons, which is far higher than any previous explosion or detonation ever created by man, and would only be superseded by yet another hydrogen bomb 7 years later, which was the “Tsar Bomba” detonated by the Soviets. The yield itself was much higher than expected, and this was caused by there being an excess amount of tritium, a hydrogen atom with 2 extra neutrons, in the fuel, which catalyzed the reaction to an extreme, causing a much more massive explosion than would have otherwise happened. This destroyed the surrounding area and pulverized the ground into powder, leading to the massive amounts of fallout mentioned earlier.
The detonation occurred in 1954, in the midst of the Second Red Scare in the US, where tensions with the growing nuclear power of the Soviet Union were ramping up extremely quickly. This test was meant to be of the utmost secrecy and more be a proof of concept as to how powerful a hydrogen bomb could be. With the Japanese sailors and the Marshallese being affected and spreading news of the detonation around the world, it wasn’t long before the Soviet Union found out about the detonation, and successfully copied the design of Bravo to use for their own hydrogen bombs. A test so close to what might be perceived as a communist or Russian sphere of influence out in the Pacific like that was met with concern and admonishment from the Soviets, seeing this as a potential outclassing of their own nuclear arsenal. This only increased tensions between NATO and the Warsaw Pact, and would result in destruction the likes of which had never been seen before with weapons such as the “Tsar Bomba” in 1961, which had a yield of around 50 megatons.
CASTLE Bravo showed the world just what kind of destructive power hydrogen bombs can contain, and that we should all be very afraid of using them, lest we annihilate all we have built. The crater that the bomb left is there, a semi-permanent scar on the earth from where man tried to recreate the sun.4 The nuclear material from the site was dumped into a steel dome not far from the area, and is somewhat contained for the moment. However, it remains to be seen if it will totally leak out into the surrounding water. Bravo triggered a hydrogen bomb arms race with the Soviet Union that wouldn’t end until basically the collapse of the country in the 90s, as several treaties were signed, but none of them explicitly banned nuclear proliferation, despite some like the Partial Nuclear Test Ban Treaty banning atmospheric testing, in an effort to combat ecological collapse. The detonation also showed the world that there was a new method of destruction that was more effective than any other in human history, and countries around the world attempted to procure these weapons in order to be taken more seriously and to defend against other countries attempting to push them around. This has led to the current situation of nuclear armament around the world, although in recent years, denuclearization efforts have led to some nations reducing their stockpiles by decent margins.5 Ultimately, CASTLE Bravo was the first real showcase of what nuclear weapons could do, and led to the last 70 years of nuclear policy worldwide.