#dw unit

The usual ground rules apply here. Anything seen on tv, happened. I can recontextualize as much as I want but it still has to fit with everything we see onscreen. I also have to use all of an EU source if I use it. No picking and choosing bits.

A quick list of stories I will be referencing:

Tv:

The Abominable Snowmen: A second Doctor tv story that sets up The Web of Fear

The Web of Fear: A second Doctor tv story that introduces the Brigadier (but before he gained that rank)

The Invasion: A second Doctor tv story that features the Brigadier

The Time Warrior: The Third Doctor tv story that introduced Sarah Jane Smith and also features the Brigadier

The Pyramids of Mars: A Fourth Doctor tv story with Sarah Jane Smith as the companion

Mawdryn Undead: A Fifth Doctor tv story that features the Brigadier

The Day of the Doctor: An Eleventh Doctor tv story that makes an in-universe reference to the dating controversy

Flux: A Thirteenth Doctor tv story that briefly features the Brigadier (again, before he gained that rank)

Expanded Universe:

Interference: A BBC Eighth Doctor Adventures book featuring the Eighth Doctor and Sarah Jane Smith (and a few others, but those tow are the only important ones for the narrative today

The Enfolded Time: A short story in the Lethbridge-Stewart series (a prose series published by Candy Jar Books that stars Brigadier Lethbridge-Stewart and other creations and IPs from the writing pair of Mervyn Haisman and Henry Lincoln)

The Split Infinitive: A Seventh Doctor audio drama published by Big Finish as a part of The Legacy of Time - an audio box set celebrating 20 years of Big Finish making Doctor Who audio stories.

An in-depth explanation of the discrepancy

The Brigadier and UNIT were primarily onscreen in the Third Doctor era, which ran from 1970-1974. The behind-the-scenes intentions from that era were that these stories took place "like ten years in the future" (which includes some really hilarious 70s guesses as to what the 80s would be like) but there also were never any direct references to this - with script editor Terrace Dicks deliberately avoiding giving dates in an attempt to avoid this exact sort of continuity error. Because of this, the only stories to make this intention of being set in the 80s explicit were in a couple Second Doctor stories and a Fourth Doctor story.

To elaborate, the 1968 story The Web of Fear features a character named Edward Travers. Travers had previously appeared in the story The Abominable Snowmen, which was definitively stated as taking place in 1935. In The Web of Fear, Travers references the events of The Abominable Snowmen being "over 40 years ago", putting The Web of Fear in 1975 or later. As mentioned above, this was the first appearance of Alistair Gordon Lethbridge-Stewart, then a Colonel in the regular army. The character would next appear, having been promoted to the rank of Brigadier, in The Invasion. In The Invasion, Brigadier Lethbridge-Stewart tells the Second Doctor it has been four years since he has seen the Doctor last, putting The Invasion at 1979 at the earliest. The Invasion is also notable for being the first story to feature UNIT, with it is implied that UNIT was founded in response to the events of The Web of Fear. Lethbridge-Stewart's involvement in UNIT explicitly as a result of his actions during The Web of Fear, which will become vaguely important in a bit

The Fourth Doctor story I mentioned above is the 1975 story The Pyramids of Mars. While it does not feature the Brigadier or other UNIT staff, it does feature Sarah Jane Smith, who had been established in her introductory story, The Time Warrior, as being from the same time as the Brigadier and UNIT. In The Pyramids of Mars, Sarah Jane references being from 1980, a claim which is corroborated by the Doctor briefly taking her to the version of 1980 where the villain of the episode, Sutekh was not stopped by them, leading to a desolate wasteland.

So by current evidence, all five years of Unit stories released between The Invasion and The Pyramids of Mars took place between 1979 and 1980. This strains credulity a little bit but is still vaguely plausible. It's the next story that breaks this completely.

After his departure from the show in 1975, Brigadier Lethbridge-Stewart returns in the Fifth Doctor 1983 story Mawydrn Undead. Here it is a major plot point that the Brigadier retired from UNIT and the military in 1976, and we see him adopting a new career of a maths teacher by 1977.

So this is where it all breaks. Going by the established dates, the Brigadier retired from UNIT before he ever joined it.

The only other tv story to add to this at all is, weirdly, 2021's Flux. This story's fifth episode has a scene that shows UNIT UK being operational by 1967, with its current leader, General Farquhar, mentioning a Corporal Lethbridge-Stewart being a on staff. In theory, this should take place between The Web of Fear and The Invasion, since Lethbridge Stewart is not a Brigadier yet but has joined UNIT. This would place both The Web of Fear and The Invasion as taking place in the 60s.

This does leave out the problem that Lethbridge-Stewart was a Colonel in The Web of Fear and not a Corporal (if you don't know military ranks, a Colonel is much higher up the chain of command then a Corporal), but given that General Farquhar is repeatedly shown to be somewhat unintelligent (his main role in Flux is to get manipulated then killed by one of Flux's minor villains), I'm comfortable saying that General Farquhar misspoke when he called his new Colonel a Corporal.

NuWho stories such as The Day of the Doctor have begun playing with this concept a little bit. For example, in The Day of the Doctor, Kate Stewart, the current leader of UNIT UK mentions the events of Terror of the Zygons happening in the 70s or 80s, "depending on the dating protocol."

The Tv-only explanation

So if you just want to make the tv show to be self-consistent without bringing the EU into it...

Then I can say that Travers made the very reasonable mistake of saying "forty years" when he actually meant "thirty years." I dunno about you, but I do stuff like that all the time when I'm talking and the plot moved on fast enough that the characters didn't come back to it.

As for Sarah Jane and 1980, that's a bit weirder. But you could say that Sarah Jane was at that point from 1985 or 1986 and rounded up because she liked having a nice round number to say where she was from. This does not feel like a normal thing to do, but Sarah Jane Smith is not a normal person. And the Doctor took her to an alternate 1980 because why not it was as good a date as any for him to make his point.

So there! Now all the UNIT stories can take place in the late 60s and 70s making the dates given in Mawydrn Undead and Flux work. But if you want to have a little more fun and see the explanation that is what I consider "canon," then I invite you to keep reading.

The Expanded Universe explanation

If you thought the tv version of this was a mess, the EU is so much worse. I really do not want to go through each and every book, comic, and audio that gives a date for the time the Brigadier was in charge of UNIT - if you want to explore the full list of contradictory dates, Tardis wiki has an excellent overview here. For the record, most of the EU tends to agree with Mawdryn Undead over anything else, but even those stories that put the Brigadier leading UNIT UK era in the early 70s often disagree with each other.

Luckily for me, I can just bypass all of that altogether.

So I mentioned above that the UNIT Dating Controversy is the most notorious continuity error in all of Doctor Who, and so uh my job here is actually a lot easier because of that. My Whoniverse essays are usually trying to reconcile the EU, but the Unit Dating Controversy is a problem that exists completely in the tv show. The different parts of the EU are somewhat disinclined to pay attention to each other, and the tv show doesn't care about contradicting the EU (which, for the record, is 100% a good thing. I think trying to stay in-line with established lore would be super limiting to the series and also deprive me of getting to write these essays!), a lot more people care about the tv show being consistent with itself.

Which is why the EU has not one but two ready-made solutions handed to me on a platter.

So the first one gets seeded in the book Interference. In it, Sarah Jane Smith says she can't remember if she worked with UNIT in the 70s or 80s, and the Doctor responds by saying that, "Temporal slippage… My fault, I'm afraid. I think it's currently the 1970s, but —", at which point he is interrupted.

This is followed up with the short story The Enfolded Time, which claims that the 70s and 80s were basically scrunched into a single decade by the Doctor visiting them so much. The story states that the disturbances were settled by 1990, and has the Brigadier working with UNIT to establish a new dating protocols - the same ones Kate would later be using.

Meanwhile, the audio story The Split Infinitive (set in both the 60s and 70s) features, at the end of the story, a "temporal shockwave" that the Seventh Doctor notes would affect nearby time travelers. The Brigadier's situation of retiring in the 70s after working in the 80s is explicitly mentioned as one side effect of the temporal shockwave.

I think both explanations are true. The temporal shockwave damaged the timezone around the 70s enough to weaken spacetime, so the Doctor entering and exiting the time vortex from UNIT UK's headquarters as frequently as he did caused the temporal slippage around the Brigadier and UNIT UK.