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Multi-national military force whose mission was to deal with alien or extraordinary Earth-based threats with the potential to endanger the whole planet. UNIT was headquartered in Geneva and placed under the sole command of the United Nations. In practice, however, it was subject to the supervision of various national ministers and local authorities.

The concept of a special force to deal with alien threats probably first arose in Britain after the secret Dalek attack of 1963 (7H), and was undoubtedly reinforced by WOTAN’s failed attempt to take over London with its War Machines in 1966 (BB).

The Yeti invasion of 1969, thwarted by the Second Doctor and British Colonel Lethbridge-Stewart, was most likely the catalyst which resulted in the creation of UNIT. Now promoted to the rank of Brigadier, Lethbridge-Stewart was put in charge of UNIT’s British branch. He was ably assisted by the competent Sergeant Benton and Captain Mike Yates

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UNIT was extremely active during the early 1970s. Brigadier Lethbridge-Stewart and his men fought the Cybermen alongside the Second Doctor when they threatened to invade Earth (VV).

Soon afterwards, the Doctor was exiled to Earth by the Time Lords. Then in his third incarnation, he became UNIT’s scientific advisor.  With the help of his assistants, Liz Shaw, Jo Grant and, later, Sarah Jane Smith, the Third Doctor helped UNIT defeat the Autons (AAA), (EEE), the Silurians (BBB), the so-called "Ambassadors of Death" (CCC), Prof. Stahlman’s "Inferno" project (DDD), the Master (EEE), (FFF), (GGG), (JJJ), (LLL), (OOO), Axos (GGG), Azal (JJJ), the Daleks (KKK), the Sea Devils (LLL), Kronos (OOO), Omega (RRR), BOSS (TTT), Linx (UUU), Sir Charles Grover’s Operation Golden Age (WWW) and the Spiders of Metebelis 3 (ZZZ). In the last case, the Doctor regenerated under the Brigadier’s very eyes, and Captain Mike Yates, who had betrayed UNIT during the invasion of the Dinosaurs (WWW), redeemed himself.

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The Fourth Doctor, still assisted by Sarah Jane Smith, and joined by UNIT medical officer Surgeon-Lieutenant Harry Sullivan, then helped the Brigadier against Prof. Kettlewell’s Giant Robot and the Scientific Reform Society (4A), and the Zygons (4F).

At about that time, UNIT’s British HQ was moved to a priory which had been Egyptologist Marcus Scarman’s residence in 1911 AD (4G). Soon afterwards, the Fourth Doctor, Sarah Jane Smith and Harry Sullivan returned to help UNIT Colonel Faraday defeat the Kraals’ android invasion (4J). The Fourth Doctor and Sarah also helped Sir Colin Thackeray of the World Ecology Bureau and Major Beresford of UNIT destroy a Krynoid (4L).

In 1977, Lethbridge-Stewart retired from UNIT and took a job as a teacher at the Brendon School, leaving the British branch of UNIT in the capable hands of Colonel Crichton (6K). Benton, who had been promoted to the position of RSM, also left, eventually to take over a car dealership (6F).

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Later that year, Tegan and Nyssa, two of the Fifth Doctor’s Companions, met the retired Brigadier at Brendon School and, together, they traveled forward to 1983 to fight Mawdryn. The Brigadier emerged from the encounter with his future self with selective amnesia (6F).

In 1983, the Fifth Doctor used his UNIT clearance to solve the mystery of the disappearance of a Concorde airplane at Gatwick Airport (6C). Later, the Fifth Doctor met the retired Brigadier (who had forgotten their previous encounter) to defeat Mawdryn (6F). The Brigadier recovered his memory and renewed his contacts with UNIT. But Borusa snatched him and the Second Doctor (who had transgressed the Laws of Time to visit his old friend) one day before a planned UNIT reunion. Together with various Companions (including Sarah Jane Smith and illusions in the form of Liz Shaw and Mike Yates), the Brigadier helped the Five Doctors defeat Borusa (6K). Soon after that, he married his old flame, Doris.

In 1992, the Seventh Doctor and Ace teamed up with Lethbridge-Stewart and met Brigadier Bambera of UNIT fighting the sorcery of Morgaine, Queen of an alternate Earth (7N).

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