World War III

World War III, also known as the Third World War, was a conflict that broke out on planet Earth. During the second half of the 20th century and into the 21st century, fear of a third world war was usually connected to it being a potentially civilisation-destroying nuclear war. (AUDIO: Protect and Survive)

The Doctor prevented this war from breaking out prematurely on several occasions (TV: The Mind of Evil, Robot), most notably when he prevented individuals from an alternate timeline in which the war did occur in the late 20th century from making it happen. (TV: Day of the Daleks)

Adam Mitchell claimed that he nearly caused World War III in the late 1990s, when he hacked into American Department of Defense computers. (TV: Dalek)

The Slitheen family tried to cause World War III in 2006 so they could sell Earth's radioactive remains as fuel. They nearly succeeded but were killed when Mickey Smith blew up 10 Downing Street with a missile on the Ninth Doctor's orders, killing them. (TV: World War Three)

It is known that, at some point in Earth's history, a conflict known as World War III broke out as World War IV occurred prior to the 25th century (AUDIO: Frostfire) while World War V occurred during the 49th century (AUDIO: Singularity).

Alternative timelines
In an alternative timeline created by the Elder Gods in the hope of destroying Earth, World War III broke out on 9 November 1989 between the United States and its allies including the United Kingdom on the one hand and the Soviet Union on the other hand. Given that nuclear weapons were used by both sides, hundreds of millions of people were killed in the conflict. This timeline was ultimately negated by the Seventh Doctor except for in a pocket universe where the Doctor trapped the two Elder Gods responsible (and, accidentally, his companions Ace and Hex). (AUDIO: Protect and Survive)

In an alternative timeline, it was thought that U.S. President John F. Kennedy would have started a nuclear war on 22 January 1964 if he had not been assassinated on 22 November 1963. (PROSE: Who Killed Kennedy)

In another timeline, a 22nd century anti-Dalek resistance fighter named Shura travelled back to the 1970s and set off a dalekanium bomb which destroyed the World Peace Conference. World War III started as various global factions accused each other of having done so. In the aftermath, the Daleks conquered and ruled over the survivors, resulting in the world that Shura had tried to prevent from coming to pass in the first place. However, the Third Doctor undid the damage by ensuring that when the bomb went off, the delegates had already left. The Daleks and Ogrons who had travelled back to the Conference were killed by Shura's bomb. (TV: Day of the Daleks)