Great War

The Great War (not to be confused with World War I), started (and ended) on October 23rd, 2077. It is not known, however, who dropped the first bomb. It lasted two hours, but was unbelievably destructive. More energy was released in the early moments of The Great War than all previous conflicts in the history of the world combined. Although lasting a very short time, this is appreciated as World War 3 given the mass destruction of the Earth and most of its inhabitants.

Events before the Great War
The situation leading to the war included China invading Alaska, and the United States' annexing Canada. The European Commonwealth reacted to the Middle East's raising of oil prices by taking military action. As the United Nations tried to keep peace, many members pulled out of the UN, and within two months of this the UN was disbanded. This period of conflict was called the Resource Wars. Many smaller nations went bankrupt in the ensuing conflict. The Resource Wars were ended by The Great War.

The Great War
The Great War itself began when nuclear weapons were launched by all capable nations, (mainly America and China) and lasted around two hours. Once over, the world fell into the darkness of a nuclear holocaust. The west coast of the United States was hit first, and as a consequence some on the eastern coast were able to get into the Vaults and personal protection shelters. In the two hours of nuclear fire, the geography of the planet changed significantly. Entire mountain ranges were created as the earth buckled and moved under the strain of such cataclysmic pressure. Rivers and oceans around the world were contaminated with radioactive fallout, thus the only SAFE water to drink was what was scientifically purified. Vaults were incorporated with water purifiers to keep the occupants free of radioactive contamination.

The aftermath
However, despite the global destruction, many areas remained habitable. Humans were in some parts able to continue living in the ruins, establishing communities and even cities. (Vault City with the help of GECK). Some major cities were not completely destroyed in the explosions, and areas such as Washington DC had some intact buildings. However, most streets were and continue to be blocked with rubble. This creates a challenge when moving around above ground. Many of the Metro systems remained intact, while some were blocked, they remain the easiest way to move around Washington D.C.

The Vaults, with the exception of Vault 101, opened after the two hours of the Great War. In Fallout 3, various human remains look like they could be pre-war can be found in the the various Metro tunnels, along with old beds, and desks. This may imply that some citizens tried to live out their lives underground. This could also explain how several above-ground communities re-started, as any humans on the surface would have been annihilated by the nuclear blasts, thus the underground settlers could then begin rebuilding communities. (This however, remains as a theory only.) It is also possible that a large number of the feral ghouls that roam the sewer systems were also products of these doomed attempts to rebuild civilization. Around a week after the initial nuclear explosions, rain started to fall, however none of it was drinkable. The rain was black; tainted with soot, ash, radiation plus various other chemicals found in nuclear weapons. This marked the start of fallout. The rain lasted days, killing thousands of species, be they animal, plant or micro-organisms. Those who survived after the rain were left to the now barren Wastelands, where nearly all plant life had died from the intense radiation.

Plenty of deaths
Many citizens did not heed the air raid sirens, as they believed it was just another drill. The Vaults (not including Vault 12, which was never intended to shut) sealed themselves as the Earth burned. A few citizens that took the air raid sirens seriously, but did not have access to vaults, made their way to various locations that they felt would be safe from the bombs, like sewers and subway stations, fallout shelters incomparable to the vaults, or in the case of the Keller Family, the National Guard Depot. However, without a very strong outer shield to defend them from both the blast and the heat of the blast(such as Lamplight Caverns or Raven Rock), very few would survive, and a few became ghouls, or ghoul communities. It has been seen that some families actually survived a couple of years in drainage centers, as seen after activating the radio signal Oscar Zulu, which Bob Anderstien needed help for his family. Those who had already earned their admission into the Vaults went into them. Those who did not, however, were left to the mercy of the bombs and their own nearby fallout shelters. A female ghoul named Carol in Underworld in Fallout 3 claims "My family did not have much money, so we could not get into a vault." It seems only the moderately wealthy could buy their way into a Vault at the time of The Great War, though according to letters discovered in mailboxes, many of those who could afford it were not granted space, due to the lack of time Vault-Tec had to build. This is because Washington D.C.'s Vaults were filled to capacity, while Vaults located in states like Oklahoma were nearly unoccupied.

The great downfall
After the bombs fell, the world "fell under a blanket of nuclear fire and radiation, and was silent for many years to come".

At least the world's two super powers, the United States and China being 'carpet nuked', and possibly as well as Europe, the Soviet Union, other nations of Asia such as Korea and Vietnam, and possibly the then newly annexed Canada. Smaller nations of the earth felt the changes of the Great War in a different way. Destabilization and economic collapses rendered countries such as Australia, New Guinea, and the continent of Africa were spared from the majority of the nuclear missiles and as such much safer from the radioactive fallout. However, the gradual undertaking of reinstating the world became too much and after several civil war's these countries retreated (still quite intact) but nethertheless into isolation. (Though there were American troops, and Vault-Tec Vaults, it is unclear whether China would attack Canada with unconventional weaponry, due to the large amount of oil that may have been still available.)