Over the course of just four days in 1945, enormous horrors were perpetrated over the Japanese cities of Hiroshima and Nagasaki. Horrors that can be traced back to this complex in Los Alamos, New Mexico, where the Manhattan Project was housed. It was here that some of the brightest minds gathered to develop the atomic bombs later named "Fat Man" and "Little Boy."

Far from Los Alamos, the test bombs were getting manufactured and being tested, on Tinian — an island that makes up the Marianas. The island was seized from the Japanese by the Allies after the Battle of Tinian in 1944, and turned into a bomb factory. These soldiers are examining the casing on a such a test bomb for any vulnerabilities. 

On the left is Francis Birch, one of the authors of the atom bomb and a participant in the brain trust that was the Manhattan Project. His primary contribution was in the fuze in the nozzle that would explode near impact. Right now he's marking up the bomb that would become the bomb Little Boy, successor to the failed Thin Man test. On the right is Norman Ramsey, a future Nobel Prize-winning physicist, whose work consisted mainly of the compatibility of the bomb and its bomber transporter.  

A technician is seen soldering the nozzle of "Fat Man" to make sure it's secure. The nozzle on this implosion-style nuclear weapon must be air-tight to create the vacuum necessary for maximum explosion on impact. "Fat Man" got its name because of its shape — wide and bulbous. 

Norman Foster, like others, signed his name on the bomb — like an artist might autograph a work of art. "Little Boy" would be used on Nagasaki, a valued seaport and thus a significant wartime landmark. The death toll after the bomb dropped is estimated to be somewhere between 30 and 40,000.  

Other technicians, soldiers and scientists signed their names onto the exterior of the death machine. The Manhattan Project itself maintained a level of extreme secrecy about it, and an expose after the war estimated that only a handful at high levels knew of the full extent of its activities. But here some of those involved are, signing the check.  

Here, "Fat Man" is lifted onto a transport trailer and scrutinized one last time before it will be taken outside for loading. The bomb itself weighed over 10,000 pounds, and featured a plutonium core. The fission reaction that would ensue would release the equivalent of 21 kilotons of TNT.  

"Fat Man" is transferred onto a transport vehicle and taken to the North Field airbase on Tinian. The island is believed to have first being invaded by Magellan in the middle of the 17th century. After the natives responded to the incursion on their soil with a counterattack, Magellan sent a small team out to burn native houses and kill those inside. So, it has a history of Western colonization.  

This is North Field, the airbase on Tinian. "Fat Man" gets poised to be lowered into a trench that was specially designed for its dimension. It will remain there until it's time for relocating onto the bomber that will let it drop on Nagasaki. A number of famous air raids, fire bombings, and ballistic Superfortresses originated in North Field. 

Today it's a tourist attraction.  

The sites for "Little Boy" and "Fat Man" have been converted to memorials since the war. To wax poetic: the trenches come across as funereal pits, making the bombs that were briefly entombed there angels of death that rose from the grave. Visitors to Tinian rave about these sites.   

Here she is. The Enola Gay, the surrogate mother that will be carrying "Little Boy" over Nagasaki until the moment of discharge is at hand. The B-52 Superfortress bomber taxis over the pit, ready to receive her burden. 

With Enola hovering over it, "Little Boy" is readied for loading. Technicians unveil the tarp from the bomb as they would a veil over the deceased, and double-check access points. There's no turning back now.  

Lifting that massive weight off the ground takes more than just a fulcrum and a lever, as Archimedes would have it. It requires an hydraulic lift that can do the trick. Such a one is used to get "Little Boy" inside its temporary womb. 

"Little Boy" now inside the Superfortress, a technician performs one last checkup on the holsters. You wouldn't want it coming loose while in transit. Premature ballistic ejection would not be ideal.  

On August 6, "Little Boy" was dropped over Nagasaki, detonating a blast that was the equivalent of 9,700 kilotons of TNT. Three days later, on August 9, "Fat Man" was dropped on Hiroshima. On August 15, Japan surrendered, bringing an official and eventual end to the war on September 2. And only 3 percent of the global population at the time had perished.