Rising from the ashes of the Eugenics Wars of the mid-1990s, the era of World War III was a period of global conflict on Earth that eventually escalated into a nuclear cataclysm and genocidal war over issues that included genetic manipulation and Human genome enhancement. World War III itself ultimately lasted from 2026 through 2053, and resulted in the death of some 600 million Humans. By that time, many of the planet's major cities and governments had also been destroyed. (ENT: "In a Mirror, Darkly, Part II"; Star Trek: First Contact; VOY: "In the Flesh")
The war was fought in an era where various factions were known to control their military with narcotics. (TNG: "Encounter at Farpoint") Among the parties involved was the Eastern Coalition (also referred to as "the ECON"), whose direct attacks included those against the United States of America. (Star Trek: First Contact) In 2026, at the start of the war, Colonel Phillip Green led a faction of eco-terrorists that was ultimately responsible for the loss of 37 million lives. (TOS: "Bread and Circuses", "The Savage Curtain"; ENT: "In a Mirror, Darkly, Part II")
- Some of this information, such as when the war started and its basic causes, comes from an historical archive screen seen in "In a Mirror, Darkly, Part II". The death toll matches the "despotic" deaths mentioned by Spock in "Bread and Circuses" as being from WWIII. See the Eugenics Wars for a discussion of Spock's comment on the "last so-called world war" from "Space Seed."
Colonel Green's activities during the war are often cited as "genocidal" and treacherous. He and his troops personally killed hundreds of thousands of individuals affected with radiation sickness and other "impurities," using as a rationale that it was necessary in order to prevent their passing on such traits to later generations. (ENT: "Demons", "Terra Prime") He was notorious into the 23rd century for striking at his enemies in the midst of negotiating with them. (TOS: "The Savage Curtain")
Despite an escalating and ongoing global conflict, manned space exploration continued into the early 2030s with at least one mission to Mars. (VOY: "One Small Step") The New United Nations was also founded during these early years of World War III, and was among the first attempts to rebuild humanity during this era; for instance, by 2036, it had declared that no Human being would be held accountable "for the crimes of their race or forebearers." But not everyone would heed or respect this decree and some parts of world would later "abolish all United Earth nonsense." (TNG: "Encounter at Farpoint")
Humanity eventually turned over a new leaf when a few courageous people began to realize they could make a difference. (ENT: "Judgment") The war finally culminated circa 2053, when several of Earth's governments met in San Francisco to declare a cease-fire, effectively ending the war. (ENT: "Demons") As a result of this world war, like the two that came before it, whole generations were nearly wiped out. (ENT: "Judgment") The subsequent use of nuclear weapons engulfed Earth with a immense dust cloud, which ultimately resulted in numerous nuclear winters. (TNG: "A Matter of Time") When it was over, Earth was irradiated with a detectably-heightened amount of radioactive isotopes in the atmosphere. (Star Trek: First Contact)
In 2063, a short time after Earth emerged from this global war, first contact was made with the Vulcans, leading to increased recovery from the war for parts of the world. (Star Trek: First Contact) When news of this event reached Vulcan, some Vulcans, including V'Lar, were fascinated by humanity, but also worried, believing the idea that Humans had deemed themselves ready to join the interstellar community, so soon after the war, seemed premature. (ENT: "Fallen Hero") Indeed, for several years after first contact, various parts of Earth were still affected by what became known as the "post-atomic horror." In 2079, for instance, one such culture reverted to a state of near-barbarism that followed the credo: "[Kill] all the lawyers," and "[Guilty] until proven innocent." (TNG: "Encounter at Farpoint") Due to these and other factors, parts of Earth continued to be in – as Captain Jean-Luc Picard put it in 2365 – "chaos" well into the early 22nd century. (TNG: "Up The Long Ladder")
The post-atomic horror gave way to the stirrings of new attempts at establishing various unified world alliances, including the European Hegemony in 2123. (TNG: "Up The Long Ladder") These alliances would eventually be instrumental in the establishment of the United Earth Government in 2150. (TNG: "Attached")
By the early 2100s – less than two generations of the post-atomic horror – humanity was finally able to eliminate most all poverty, disease, war and hunger. Along with it a lot of other things disappeared from humanity, including hopelessness, despair, and cruelty. (TNG: "Time's Arrow, Part II"; Star Trek: First Contact; ENT: "Broken Bow")
The legacy of the war was felt in many ways during the hundred years after its conclusion. It was the subject of many films during that time, and in 2153 one of these epics won a majority of movie awards. (ENT: "Home") In the early 22nd century, the philosophy of Neo-Transcendentalism was founded by Liam Dieghan; he advocated "a return to a simpler life" in response to the war's carnage. (TNG: "Up The Long Ladder") The war additionally influenced the powerful xenophobic movement of the mid-22nd century on Earth known as Terra Prime. Led by John Frederick Paxton, the organization drew inspiration from the war through adoption of Colonel Green's goals and teachings concerning a "pure" Human race. It also blamed the Vulcans for not stopping the war with their superior technology, and thereby saving the lives of hundreds of millions of people. This blame was then channeled into a general distrust of all non-Humans. (ENT: "Demons", "Terra Prime")
In 2372, Admiral Leyton described the threat of the Founders of the Dominion infiltrating Earth and its facilities as being "maybe the greatest danger it's faced since the last world war." (DS9: "Homefront")
Following Miles O'Brien and Kira Nerys visit to San Francisco during an alternate 2048 (where the Bell Riots had not occurred) in DS9: "Past Tense, Part II", O'Brien had noted that that was "not the mid-21st century that [he] had read about in school," adding "Earth history had its rough patches, but never that rough." It would be interesting to know what O'Brien saw that was more "rough" than a nuclear war responsible for 600 million casualties.
Like the Earth-Romulan War, very few details have been presented in Star Trek on this event. In 1996, World War III received a Trekker's Choice Award for the 'Oft Heard but Never Seen' Award, as being "the favorite historical moment only alluded to in Star Trek."
According to the 40 Years of Star Trek: The Collection auction catalogue, during the middle of ENT Season 4, plans were in place for an episode to feature Colonel Green. It was planned to link Q's World War III uniform to the Colonel by having the emblem on Q's hood appear on flags representing Green. Such a flag was created for "In a Mirror, Darkly", and seen in the briefing room aboard the ISS Enterprise. When Enterprise was canceled, plans for the episode fell through and all that remains of the link between Q's uniform and Colonel Green is the flag seen in the mirror universe.