20th century
{{aquote|Bones, do you remember the twentieth century brush wars on the Asian continent? Two giant powers involved, much like the Klingons and ourselves. Neither side felt could pull out. ""Yes, I remember. It went on bloody year after bloody year.""What would you have suggested, that one side arm its friends with an overpowering weapon? Mankind would never have lived to travel space if they had. No. The only solution is what happened back then. Balance of power.|James T. Kirk and Leonard "Bones" McCoy|2268|A Private Little War}}

The 20th century''', defined in the calendar of Earth as the period from 1901 to 2000, was a violent and tense time on Earth, with major conflicts like World War I, World War II, the Cold War and the Eugenics Wars. The dominance gained by the United States of America during these wars would prove to be a crucial circumstance in the prehistory of the Federation.

 Decades 

Major events 

 In North Carolina on Earth, the Wright brothers conduct the first ever powered manned flight by Humans. (ENT opening credit sequence; )

 Embarking a new era of technological warfare, World War I is fought on Earth from July 1914 until November 1918. (; )

 Albert Einstein devises his Theory of General Relativity, a cornerstone for Humans developing technologies like the transporter and warp drive in the future. ()

 A civil war breaks out on the planet Xindus, which lasted until the 2030s. ()

 World War II begins on Earth when the nation of Germany launches an invasion of neighboring Poland.

 Following German and Japanese aggression against their territories and peoples, the Earth nation known as the Soviet Union abandons its alliance with Germany and the United States of America abandons its official policy of neutrality and both enter World War II on the side of the Allied Powers. 

 World War II ends with the United States of America being among the victors. (; ; )

 A Ferengi shuttle from the 24th century crashes on Earth near Roswell, New Mexico, leading to unofficial first contact between Humans and Ferengi. The "aliens" eventually escape and the event is covered up by the USA. ()

 After their first contact earlier this century, a border dispute begins between Andoria and  which lasts for the next two hundred years. ()

 Sputnik 1 becomes the first Human-made satellite to be launched into Earth's orbit. An investigating Vulcan ship crash-lands on Earth near Carbon Creek, Pennsylvania, leading to unofficial first contact between Humans and Vulcans. ()

 The National Aeronautics and Space Administration is chartered by the United States of America and remains Earth's premiere spacefaring organization until the founding of the United Earth Space Probe Agency, ca. 2067. It is responsible for the space exploration missions which involved the launching of Voyager 6 during the late 20th century and Charybdis during the first half of the 21st century (in 2037). (; )

 After Gary Seven secretly sabotages the launch of an American orbital nuclear warhead platform, a new and stronger agreement against the use of such weapons is made. ()

 The Earth spacecraft Apollo 11 lands on the Moon, recording Humanity's first steps on another world. (; )

 The European Space Agency is established with France among its ten founding member nations. ()

 Dr. Gillian Taylor of the Cetacean Institute in Sausalito, California, protects, exhibits and studies two Humpback whales, a Terran endangered species. Also, Dr. Nichols of Plexicorp invents transparent aluminum. ()

 Having cost the lives of over thirty million Humans, the Eugenics Wars, brought about in 1993 by a group of genetically-engineered "supermen" lead by Khan Noonien Singh, come to an end with their defeat. Khan and over fifty of his followers leave Earth aboard the . (; ; ; )

 The International Space Station is completed and is an international effort between fifteen nation-states, including the United States of America, Canada, Russia, and Japan. ( opening credits)

 Events without specified years 
 Judge Crater disappears from Earth under mysterious circumstances. ()
 First contact occurs between Vulcans and Andorians during the early 20th century. According to the Vulcans, it "seemed promising," "despite their heightened emotions." However, it was soon discovered that "they were duplicitous," wishing to only honor "agreements that didn't conflict with their interests." ()
 According to Q, in this century, nations on Earth are fighting each other for territorial gains. ()
 The later half of the 20th century is dominated by a cold war as well as several small conflicts in Asia called the Brush Wars. ()
 The Denobulans start to use genetic engineering to "generally positive effect". ()
 In Human games, the penalty box is introduced. ()
 Music styles that originated in this century include jazz, crooning, and rock and roll. Composers and musicians include John Philip Sousa, Irving Berlin, and Gustav Mahler.
 While film recordings were pioneered in the 19th century, the 20th century sees the first major movie productions including The Andromeda Strain, The Black Cat, , and The Day the Earth Stood Still, and later the first televised broadcast including series like I Love Lucy, Mission: Impossible, The Three Stooges, and The Twilight Zone''.
 In the 20th century, cars, tanks, aircraft, and helicopters become commonly used.
 The .38 police special is introduced into service for use by law enforcement agencies on Earth. ()
 Arthur C. Clarke derives Clarke's Third Law. ()

Appendices

20th century productions 
 
  
  
 
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External links 
 
 

cs:20. století
de:20. Jahrhundert
es:Siglo 20
fr:20ème siècle
it:XX secolo
nl:20e eeuw
pl:XX wiek
pt:Século XX
sv:1900-talet