Someone mentioned recently that Teutschland was an archaic name for Deutschland and could be used to (ironically) highlight certain aspects of the country's culture, history, etc. A cursory search in Google didn't turn up anything substantial. The German Wikipedia article for Teutschland simply redirects to the main article for Deutschland, but the topic/word is not discussed in the article.
What would a speaker want to imply or express by choosing to use Teutschland as opposed to Deutschland?
"Teutschland" is in fact an old spelling of "Deutschland". The designation "deutsch" originates from the Old High German word "diutisc", which meant "belonging to the people". In short, the meaning was to differentiate speakers of Germanic languages like Franconian or Gothic from their neighbors who spoke Romance languages. Over the centuries and in different areas, several different spellings were used, some beginning with "deu-", some with "teu-", some with "doi-", some with "toi-" and so on.
Today, the correct spelling is "Deutschland". Other spellings are sometimes used in historical contexts or in yearning for supposedly better "olden times": "When William II was Emperor, such a thing wouldn't have happened!" Those "olden times" do not necessarily refer to the Third Reich or the German Empire, but can refer to about any period in German history.
Mostly though, other spellings of "Deutschland" are in my experience used today to mock somebody who supposedly yearns for those "olden times" or has backwater or far right views. Say for example, in a story there's a character who can't keep up with the changes in modern society, and doesn't intend to. Such a character could be saying things like "That's not the way things are done in Doitschland!!!".
Teutschland is a variant of Deutschland used in older styles of writing before spelling began to be standardized around 1850. For example in this text from 1745 you can see that the name is used beside Deutschland and other names: https://de.wikisource.org/wiki/Zedler:Teutschland
Unfortunately I'm not really sure about the etymology of the word but I think it stems from late middle high german Tiutschland which spawned these different variants. (I can't find any english sources for this but a german one is here https://de.wiktionary.org/wiki/Deutschland)
Today the word is mostly used in an academic - historic context and means that you are talking about Germany from the middle ages until around 1800 because it was the usual way of writing it at that particular time.
In a modern context you could use the word to describe something that is wrong in Germany and seems out of time and archaic or to mock someone that wants to return to these old times. However it's really rarely used because most people won't understand the reference or even know the word.
"Teutsch" is used to suggest that german nationalism has gone overboard with someone. This is not particularly recent, either - Kurt Tucholsky wrote (in 1923,) about post-WW I Germany:
Da steht eine ganze Nation. Sie ist krachen gegangen, weil sie teutsch war, statt deutsch zu sein – und statt sich zur Abkehr zu wenden, glaubt sie, es liege daran, daß sie noch nicht teutsch genug war.
wich roughly translates as:
There stands a whole nation. It went down the drain because it was "teutsch" instead of "deutsch" - and instead of turning back it believed that this (sc. the lost war) was because it hadn't been "teutsch" enough.
I can't comment on the German language use of the 'T' over 'D' as I have little to no knowledge of the subject of language. However, as a historian working on my book, Grass before Breakfast: The History of the Code of Duelling, I would like to bring some text to light: Firstly, that of CAIUS JULIUS CAESAR whom wrote a series of books called Commentaries in 50BC (approx) and whom regularly refers to the 'Teutonis' or 'Teutones' and 'Teutonum' in Latin, meaning the Teutonic German ancestors whom invaded Italy around 102BC with the Cimbri. There's a literal translation in the book, CAESAR'S Commentaries ON THE GALLIC WAR by FREDERICK HOLLAND DEWEY, A. B., published in 1916. You can find this easily on archive.org. Secondly, however, the reason for citing this is there is another earlier translation of the same works by William Duncan and LEONARD SCHMITZ, called "The Commentaries of Caesar Translated into English", published in 1852 whom state, on Page 356: "Teutones, or Teutoni, an ancient people bordering on the Cimbri, the common ancicnt name for all the Germans, whence they yet call themselves Teutsche,and their country Teutschland." I do not know if this is a bold assumption on their part or merely a coincidence, but I thought to share it with you all. :-)
