The Global Conflict of 2040 was a short-lived, but deadly, third world war that occurred some 20 years prior to the events of Thunderbirds Are Go!. Not much is known about the war (including facts like who the instigators and leaders were, where the major conflicts were fought, etc.), except that the end of the war created the World Council, a peacekeeping organisation with jurisdiction over the entire planet. The war created a more peaceful and cooperative world, including the removal of all nuclear weapons in existence and the discontinuation of nuclear as a power source.
Despite the war's end, relics from the war waiting to be discovered continue to exist, including functional weapons.
A relic from the war: a nuclear bomb that stayed in Earth's orbit.
Episodes referencing the war[]
In Space Race, a stealth mine orbiting the Earth is picked up by Thunderbird 3 during a space junk cleaning. Alan Tracy tries to survive against it throughout the entire episode. Brains claims that the mine was left over from the war. The fact that stealth mines created for use outside the Earth's atmosphere during the war would mean that various battles throughout it happened in space.