WI: Sigismund the Old, king of Poland, Lithuania, Bohemia, and Hungary

Vladislaus II had a stroke in 1504 which, given his age at the time, very well could have killed him. Let's say it does. His daughter Anne is 1 year old and Louis II hasn't been born yet, while Vladislaus' younger brother Sigismund (future Sigismund I of Poland and Lithuania) was the duke of Glogau and Troppau at the time and was made governor of Silesia and Lower Lusatia that same year. What are the chances of him being elected king of Hungary and Bohemia?

Furthermore, let's assume the succession in Poland and Lithuania follows its OTL trajectory. What is the likelihood of Sigismund becoming the king of Bohemia and Hungary AND Poland and Lithuania? Would the powers that be in any of these Jagiellonian realms be inclined to accept this arrangement? This inheritance also covers an exceedingly vast swathe of Eastern and Central Europe, would its combined might make it easier to keep the Turks at bay or would its unwieldy size distract from resolving Hungary's (or Poland's/Lithuania's/Bohemia's) institutional problems? Feel free to consider any further implications, like the opinion of the Habsburgs and Rurikids on this development or the effect this Jagiellonian mega-union would have on the diffusion of Protestantism.

@Jan Olbracht @Fehérvári @Zygmunt Stary
In regards of Hungary remember that in accordance with hungarian sucession law only the male descendants of Vladislaus were his heirs to the throne of Hungary. His broter was not. If he dies without a son the nobles are free to elect a new king - and they do not need to consider in any way or form the relations of the old king (this of course doesnt mean they wont).
 
In regards of Hungary remember that in accordance with hungarian sucession law only the male descendants of Vladislaus were his heirs to the throne of Hungary. His broter was not. If he dies without a son the nobles are free to elect a new king - and they do not need to consider in any way or form the relations of the old king (this of course doesnt mean they wont).
Yes, but Sigismund is likely to be elected as King of Bohemia (because he is Duke of Głogów and Governor of Silesia, quite popular among Czechs, and Czechs may fear troubles or even loss of Silesia if someone else is elected) before Hungary and Hungarians would likely follow.
 
This could become an Habsburg wank in fact, meanwhile France and the Protestants are so screwed ITTL...

With no prospect of inheriting Bohemia or Hungary Charles doesn't need to give Ferdinand the entirety of Austria and the mainline of the Habsburgs keep both their massive domains outside of Germany and the title of Emperor and their part of Austria. Ferdinand would inherit part of Austria, but if he is going to have a son to inherit after him is an open question, he could also join the knights or the church and have no children because of that. If Ferdinand doesn't have children or its male line is extinct the Habsburgs of Spain will marry foreign houses instead of keep marrying Habsburg with Habsburg. Also Charles can now focus everything on Germany and France, including the Austrian resources, because there is no need to bother with the Ottomans. If Sigismund or his son becomes protestant it will be a problem to Charles, but I believe that they would not want to follow this path since it would cause a lot of instability and even a two front war against the empire.

So we have a healthier Spanish Habsburg line that doesn't lose the Austrian Lands and have the imperial title. We also have the Ottomans and the Polish fighting over Hungary, Ruthenia and the Danubian Principalities, both too focused on one another to really bother with the Habsburgs. The result is that France is encircled and alone and protestantism is not allowed to spread like it did OTL, we could even have a more centralised HRE.
 
Yes, but Sigismund is likely to be elected as King of Bohemia (because he is Duke of Głogów and Governor of Silesia, quite popular among Czechs, and Czechs may fear troubles or even loss of Silesia if someone else is elected) before Hungary and Hungarians would likely follow.
Tbh, it would be better if Hungary didn't - it requires full time attention, so let it become someone else's problem
 
I would not exclude Catalina, if Fernando got the hint who England was a lost cause and had the opportunity to give her another Crown

Well, in that case there is a bunch of crowns coming with Sigismund marriage, not only one. But IOTL Ferdinand didn't give up on England and it proved itself not to be lost cause.

Well Latin was the primary court language of the Hungarian court until the end of the 18th century when it finally was replaced by German initially. Also German wasn’t as dominant in the Austrian court as you seem to make out- Italian was also an incredibly prestigious language that was used on a daily basis in Vienna.

Hungarian wasn’t really seen as the “national” language of Hungary until the 19th century- while English had cemented itself as the vernacular of England and French as that of France, Hungarians were cementing Latin as their preferred language. So Latin is probably the primary language in which the nobility communicates across regnal boundaries- of the vernaculars though, the one that eventually becomes co official with Latin is probably a west Slavic one. Old polish is still in its earliest stages as a literary language, and Czech is a little more developed and prestigious, so I could imagine a reconvergence into a west Slavic court koine as polish orthography and vocabulary picks up Czech influence.

It was primary law language but I doubt that for example in court of Vladislaus II people were speaking in Latin to each other on daily basis. And still no one thinks about Austrian Habsburgs as Italians nor anyone calls Austrian Empire Italian states. As far as Polish picking up Czech influence it started to happen IOTL for example, word citizen in Polish "obywatel" is written more in accordance to what Czech development would dictate than hyper pure Polish development would (in that case it'd be "obywaciel"), so probably ITTL the process would be sped up.
 
Well, in that case there is a bunch of crowns coming with Sigismund marriage, not only one. But IOTL Ferdinand didn't give up on England and it proved itself not to be lost cause.
Well OTL Ferdinand had no better alternative for his daughter (who was secure who God wanted her to be Queen of England) and she got extremely lucky in being able to marry Henry VIII as if Henry VII had lived a couple of years longer or Henry VIII had been more reasonable, less rebellious or less infatuated of her, he would have married Eleanor of Austria, as he should have, not Catherine
 
Well OTL Ferdinand had no better alternative for his daughter (who was secure who God wanted her to be Queen of England) and she got extremely lucky in being able to marry Henry VIII as if Henry VII had lived a couple of years longer or Henry VIII had been more reasonable, less rebellious or less infatuated of her, he would have married Eleanor of Austria, as he should have, not Catherine

I don't think Catalina is impossible, I just think Joanna of Naples would be way easier match to pull off.
 
I don't think Catalina is impossible, I just think Joanna of Naples would be way easier match to pull off.
Joanna is five years older than Catalina and I doubt who Sigismund will take her when Catalina‘s engagement is broken (and that would happen in June 1505 so in a moment in which Germaine also could still be on the table for Sigismund)
 
I would predict a 2nd Hungarian Succession war between Maximilian and Sigismund with Sigismund taking the crown of Bohemia.
Add in John Corvinus to that mix. He died in a post-battle plague outbreak on the Southern Frontier in late October, 1504. It's unlikely he would be fighting Ottoman incursions at this point in the given scenario. He would probably enjoy the support of the Újlaki(Ilok) and Frangepán(Frankopani) families.

He might actually act as the kingmaker though, standing behind Sigismund in a united front against Maximilian.
who would be top dog in that union and which culture would be dominant in court?
I think the Court would inevitably be located in Hungary, considering how crucial the quick travel of information was in regards to the Turkish threat. Not to mention, the shine of the Buda Castle was rather alluring. AFAIK, even Maximilian considered moving his place of residence to Buda had he managed to win the Hungarian crown.

Not to mention, despite the hardships it was facing, Hungary was probably still the strongest out of the four realms in question, which is another good reason for it to be the centre of the union.

And if the Court is in Hungary, then the simple matter of proximity would inevitably give an edge to the Hungarian culture in terms of Court presence. The union's real Lingua Franca would be Latin though, IMO.
2) With POD mere generation before Mohacs, Hungary is already in decline and Hungarians would be outnumbered by Slavs in Sigismund's realm by order of magnitude. And it is way easier for any Slav to learn Polish than Hungarian.
2) Was it in that severe decline? At the end of Matthias Corvinus's reign it supposedly had income rivaling France (tho I don't know if they counted also lands Corvinus conquered or not).
I wouldn't say Hungary was in decline per se. Under Matthias the incomes of the treasury from Hungary reached 900k Florins in good years and 600k in most years. Under the Jagiellonians, the usual annual royal revenues of Hungary amounted to about 300k Florins, or circa 500k if the extraordinary war tax was collected that year.

This might seem like the sign of extreme decline at first glance, but that doesn't fully reflect reality. The large discrepancy in numbers mostly come from differing approaches of governance. The Jagiellonians handled incomes in a less centralised manner compared to Matthias. This meant that they allowed the various polities/subdivisions of the Kingdom to retain more of their own revenues, providing them the means (in theory) to organise their defences locally.

Now, wether the Jagiellonians engaged in this type of governance by their own volitions is another question. I personally think it was primarily the product of circumstances. After all, prior to his stroke and then the tragic death of his wife, Vladislaus II was a surprisingly energetic ruler with a strong hand. Sure, the 1491 peace with Maximilian was humiliating (which was pretty much the cause of the Black Army's disbanding), but he proved to be very successful in subduing his domestic opponents. He tricked/outmaneuvred Beatrix, enlisted the support of Stephen Szapolyai and Paul Kinizsi, curbed the ambitions of John Corvin and suppressed Lawrence of Ilok. Even in foreign policy he scored a notable victory against the Turks in 1503. He achieved total peace for the duration of 7 years, when even the usual skirmishes and raids were (again, in theory) strictly prohibited. I also read a claim which I couldn't verify that even Szendrő/Smederevo was handed over by the Turks (then it was lost again in 1511).

Vladislaus lost his vigor in the second half of his reign and endorsed the abovementioned decentralised style of governing. This state of affairs was perpetuated by the infancy of Louis II and the regency council. Upon Louis' maturity however, things already began to develop in the direction of recentralisation IOTL, even despite the unpopular German-orientation and the crisis on the Southern Frontier.

Should Sigismund manage to secure the Hungarian throne in 1504-'5, I believe he would be more than capable enough to rule at least as effectively as Vladislaus did until that point.
 
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I think the Court would inevitably be located in Hungary, considering how crucial the quick travel of information was in regards to the Turkish threat. Not to mention, the shine of the Buda Castle was rather alluring. AFAIK, even Maximilian considered moving his place of residence to Buda had he managed to win the Hungarian crown.

Not to mention, despite the hardships it was facing, Hungary was probably still the strongest out of the four realms in question, which is another good reason for it to be the centre of the union.

And if the Court is in Hungary, then the simple matter of proximity would inevitably give an edge to the Hungarian culture in terms of Court presence. The union's real Lingua Franca would be Latin though, IMO.

As far as the Latin is involved - I'd ask the same question I asked Madukar_Shah beforehand - why Austrian Habsburgs didn't use it as lingua franca of their union? IMHO using the language nobody knows from the birth is simply impractical and not tenable in Early Modern Era.
You have a point in rest of what you say (tho quick travel is also important on the other fronts, so Kraków has edge of roughly central localisation), especialy that revenue would be rather alluring. And I am not shocked by Max wanting to move to Buda, IMHO people in general tend to overwank Austria pre Mohacs (what gave Austria importance was civil war in Hungary) while it was nothing special.
 
As far as the Latin is involved - I'd ask the same question I asked Madukar_Shah beforehand - why Austrian Habsburgs didn't use it as lingua franca of their union?
What do you mean? Latin was the Lingua Franca of the Habsburg Monarchy. It was the language of state administration and of interstate communication until Joseph II's reforms. German was the prevalent language in the Court, sure, but as it has been pointed out, Italian was also in common usage (atleast in the 16th century). As for why German was much more common compared to Hungarian or Czech, there are a number of reason:

> Proximity. The capital was in Vienna, within Germany.
> German was more widely spoken, had greater literary tradition and had higher prestige.
> The Viennese Court was also the court of the HRE, making the number of German subjects of the Habsburgs dwarf the number of Hungarians and Czechs.
> Hungary was a rump state, half of the remaining state was independent from the Habsburgs, so the number, weight and influence of the Hungarian nobility was far smaller than it otherwise could have been.
> Religious divide. Most of the Czech and Hungarian nobility were non-Catholics(Hussites and Protestants) and therefor unfavoured. Most of the remaining Catholics were Germans.
 
What do you mean? Latin was the Lingua Franca of the Habsburg Monarchy. It was the language of state administration and of interstate communication until Joseph II's reforms. German was the prevalent language in the Court, sure, but as it has been pointed out, Italian was also in common usage (atleast in the 16th century). As for why German was much more common compared to Hungarian or Czech, there are a number of reason:

> Proximity. The capital was in Vienna, within Germany.
> German was more widely spoken, had greater literary tradition and had higher prestige.
> The Viennese Court was also the court of the HRE, making the number of German subjects of the Habsburgs dwarf the number of Hungarians and Czechs.
> Hungary was a rump state, half of the remaining state was independent from the Habsburgs, so the number, weight and influence of the Hungarian nobility was far smaller than it otherwise could have been.
> Religious divide. Most of the Czech and Hungarian nobility were non-Catholics(Hussites and Protestants) and therefor unfavoured. Most of the remaining Catholics were Germans.

What does it mean it was more widely spoken? Comparing overall numbers, Germans were not that numerous in aristocracy compared to overall non-German population of Habsburg monarchy and anyways, in case of Sigismund's monarchy language which is first to most of Sigismund's nobility is "Western Slavic" (Czech and Polish were often recognized as dialects of the same language by contemporaries and while Poland was poorer than Hungary it was relative in population and that + Bohemia probably makes up sizable chunk of empire's population). Well, what I've meant was that German was the most spoken language at court and overall it was language Habsburgs were most associated with. And the fact that as you said: "German was much more common compared to Hungarian or Czech"
>the first one is alright point
> the second one I've partially responded to, but Czech was already prestigious enough to compete with German, it's literary tradition dates to IXth century, when first Slavic alphabet was made in Great Moravia, so that has no bearing on issue IMHO, if length of literary tradition should be any indication, Czech would be able to compete with German in Habsburg monarchy
> HRE doesn't matter in that scheme, "subjects" should be put in quote, because emperor didn't have much control over empire and for example, being HRE did nothing to hinder the development of Czech culture when Charles IV was emperor (surely, if that was the case, Czechs should be totally germanized in XIVth century considering Charles IV did not have any other country than Bohemia itself under his rule) and it was flourishing under his rule and Charles tried to spread knowledge of Czech to Germany (for example in a monastery he founded in central Germany it was required for monks to learn Czech).
So anyways, you think the lingua franca would be Latin until XVIIIth century (I don't think existence of Sigismund's monarchy would butterfly away Englightement) and than language of whichever state would be strongest at that time?
 
What does it mean it was more widely spoken? Comparing overall numbers, Germans were not that numerous in aristocracy compared to overall non-German population of Habsburg monarchy
Maybe, but Catholic ones certainly were, especially if the HRE in its entirety is considered.
in case of Sigismund's monarchy language which is first to most of Sigismund's nobility is "Western Slavic" (Czech and Polish were often recognized as dialects of the same language by contemporaries and while Poland was poorer than Hungary it was relative in population and that + Bohemia probably makes up sizable chunk of empire's population).
The language of the Bohemian nobility was not exclusively Czech. German was prevalent too, and even dominant among the remaining Catholics of the Bohemian Crown.
most of Sigismund's nobility is "Western Slavic" (Czech and Polish were often recognized as dialects of the same language by contemporaries and while Poland was poorer than Hungary it was relative in population and that + Bohemia probably makes up sizable chunk of empire's population).
Those are valid points. Still, I can't imagine "Western Slavic" supplanting Latin as the official language of Hungary. If the Court itself wants to avoid dealing with multilingual duplicates of documents, then adopting Latin as its official language of communication would serve its purposes the best. Past that, local governorates and administrations could still translate these documents into whatever language(s) they desired.
> the second one I've partially responded to, but Czech was already prestigious enough to compete with German, it's literary tradition dates to IXth century, when first Slavic alphabet was made in Great Moravia, so that has no bearing on issue IMHO, if length of literary tradition should be any indication, Czech would be able to compete with German in Habsburg monarchy
Perhaps within Bohemia, but otherwise I don't think Czech prestige-wise was in the same playing field as German on an international scale. Perhaps others could weigh in on this particular question.
> HRE doesn't matter in that scheme, "subjects" should be put in quote, because emperor didn't have much control over empire
It absolutely does matter. The Emperor might have had very limited influence on the strongest of the princes, but the same does not apply to the rulers of petty fiefdoms. But that's actually not the focus of this point. Candidates for HRE Court and other kind of administrative or governing positions (subjected to the Emperor's discretion) were not limited to a pool of Austrian notables only. No, the pool encompassed the entirety of the (German-dominated) HRE. As such, you could see generals, politicians, administrators, buerocrats, etc. employed by the Viennese Court hailing from all over the Empire.
being HRE did nothing to hinder the development of Czech culture when Charles IV was emperor (surely, if that was the case, Czechs should be totally germanized in XIVth century considering Charles IV did not have any other country than Bohemia itself under his rule)
Putting aside that the Luxemburg dynasty was of French origin, the development of Czech culture was not hindered, but the usage of German did begin to spread among the Bohemian nobility. Hussitism created a hard division between Czechs and Germans, which did stall the Germanisation process, but once Recatholicisation efforts and absolutism triumphed during the 30YW, it was in full swing until the advent of the Czech national revival of the 19th century.
it was flourishing under his rule and Charles tried to spread knowledge of Czech to Germany (for example in a monastery he founded in central Germany it was required for monks to learn Czech).
That is certainly very interesting, but I don't think we should draw far reaching conclusions just based on something like that.
So anyways, you think the lingua franca would be Latin until XVIIIth century
If not else, the established communicating language of the Court, yes.
So anyways, you think the lingua franca would be Latin until XVIIIth century (I don't think existence of Sigismund's monarchy would butterfly away Englightement) and than language of whichever state would be strongest at that time?
No, I don't think any of the states have enough pull to force its national language on the others lastingly (without Lublin, not even in the case of Lithuania, maybe). Even the Habsburgs failed miserably to push German down the throats of Hungarians. German was official in Hungary only under Josef II from 1784 to '90, then under the Austrian occupation of 1849–'60('67).

Well, if a common Czech-Polish-Slovak identity does emerge, then the union could perhaps be violently transformed into a "Zapadoslavian Empire" sometime in the 19th or 20th century. Then West Slavic could establish itself as the sole official language in the entire formation.
 
The language of the Bohemian nobility was not exclusively Czech. German was prevalent too, and even dominant among the remaining Catholics of the Bohemian Crown.

In 1504? Most of Bohemian nobility spoke Czech (yeah, there were some Germans too, but they were minority), even in the beginning of Habsburg rule Bohemian parliament passed the law that every noble of Bohemia was supposed to know Czech and Rudolf II's letters patent to Bohemian nobility was written in Czech.

Perhaps within Bohemia, but otherwise I don't think Czech prestige-wise was in the same playing field as German on an international scale. Perhaps others could weigh in on this particular question.

Considering what "others" are in that union (Poland and Lithuania, the second one already under influence of Polish culture), yes they would weigh in because in Poland not only Czech was considered as very close, but it had enough influence that sometimes Poles conformed spelling of their words to Czech norm. And German was seen with suspicion in Poland.

Those are valid points. Still, I can't imagine "Western Slavic" supplanting Latin as the official language of Hungary. If the Court itself wants to avoid dealing with multilingual duplicates of documents, then adopting Latin as its official language of communication would serve its purposes the best. Past that, local governorates and administrations could still translate these documents into whatever language(s) they desired.

Not in XVIth century, and than it depends on internal power balance in union later on. And well, once national language of Hungary is considered, Slovaks (once they would start having elites on their own) speak it and it would be easier to learn for Croatians for Hungarian, but I would say that is very hard to tell. Equally probably, Hungarian could prevail and we could have (in TTL's 19th century) magyarization being tried all over eastern Europe.

Putting aside that the Luxemburg dynasty was of French origin, the development of Czech culture was not hindered, but the usage of German did begin to spread among the Bohemian nobility. Hussitism created a hard division between Czechs and Germans, which did stall the Germanisation process, but once Recatholicisation efforts and absolutism triumphed during the 30YW, it was in full swing until the advent of the Czech national revival of the 19th century.

It was, but Charles considered himself Czech and felt most attachment to Bohemia, tho he was Francophile to a degree (he kept name Charles who according to his own memoirs was ordered to be given to him on confirmation by Charles IV of France) and well, what you describe suits more Bohemia proper than Moravia, in Moravia even in XVIIth century, after battle of Biała Góra/White Mountain there were Czech speaking top clergy like that guy - https://cs.wikipedia.org/wiki/Tomáš_Pešina_z_Čechorodu.


, but I don't think we should draw far reaching conclusions just based on something like that.

Yeah, it's just one of the arguments I've given, not the most important.

andidates for HRE Court and other kind of administrative or governing positions (subjected to the Emperor's discretion) were not limited to a pool of Austrian notables only. No, the pool encompassed the entirety of the (German-dominated) HRE. As such, you could see generals, politicians, administrators, buerocrats, etc. employed by the Viennese Court hailing from all over the Empire.

Yeah, but the bulk of civil service of Habsburg monarchy was made up by their real subjects. The rest of HRE was only an addition.

No, I don't think any of the states have enough pull to force its national language on the others lastingly (without Lublin, not even in the case of Lithuania, maybe). Even the Habsburgs failed miserably to push German down the throats of Hungarians. German was official in Hungary only under Josef II from 1784 to '90, then under the Austrian occupation of 1849–'60('67).

In Lithuania they didn't use Baltic Lithuanian in chancellory anyways, they used Old Ruthenian but usage of Polish among elites was common even before union, even those who opposed it (Radziwiłł family) written their letters to each other in Polish.
 
Considering what "others" are in that union (Poland and Lithuania, the second one already under influence of Polish culture), yes they would weigh in because in Poland not only Czech was considered as very close, but it had enough influence that sometimes Poles conformed spelling of their words to Czech norm. And German was seen with suspicion in Poland.
I meant other members of the forum.
 
Polish was lingua franca of Eastern Europe in 17th century and was spoken even beyond PLC-it was used even at Russian court. Thus *Common West Slavic* could be even more widespread ITTL.
 
Not in XVIth century, and than it depends on internal power balance in union later on. And well, once national language of Hungary is considered, Slovaks (once they would start having elites on their own) speak it and it would be easier to learn for Croatians for Hungarian, but I would say that is very hard to tell. Equally probably, Hungarian could prevail and we could have (in TTL's 19th century) magyarization being tried all over eastern Europe.
I don’t think Hungarian really has a shot- if Hungary is the dominant kingdom/ location of monarchs main seat (which seems probable given its closest to the area that needs constant military attention), it has no need to get culturally defensive and switch from Latin to Magyar. The pod here is quite early, and things like the reformation could derail things, but the late adoption of Magyar in Hungary is not simply because the enlightenment and the vernacular revolution was late getting there, it’s because something different was going on with regards to the status of Latin in the national identity. Unlike other areas, where the vernacular was the language of the merchant class in Hungary, the language of cities was German, and Magyar was seen as the language of the nobility- famously not a group that is slow in switching languages.


But with a union beginning in 1504, I can imagine the west-slavicisation of the Hungarian elite by the 18th century, especially if Budapest is the capital. By the time of the enlightenment its not super implausible to me that any monarch who really really strongly feels that Latin has no place in a modern state would switch it out with west Slavic throughout the union, including Hungary.

I’m just gonna put some quotes from “Latin at the Crossroads of Identity: Linguistic Nationalism in the kingdom of Hungary”

The number of accounts and anecdotes of Hungarys Latin speaking population is impressive. Characteristic of this type of story is the ploughing peasant who speaks Latin to a passer-by…. Latin could indeed function as a means of everyday communication that seemed odd to foreigners. The question of how widespread and proficient everyday Latin knowledge was has been investigated by Istvan Gyorgy Toth on the basis of archival material. While he affirms that in areas where the population was mixed, especially present day Slovakia, Latin was often used as a common language, in areas where ethnic boundaries were stiffer the level of Latin was much lower. When Joseph II tried to impose German in the 1780s, 37 counties in Hungary argued to keep Latin, and only 20 for any sort of inclusion of Hungarian- in these arguments Latin was referred to as the patria lingua, language of the fatherland. While latin was embedded in the legal identity of the estates and the Catholic clergy, it was also integral to the “national identity” of another vaguely defined supra-ethnic group, the Hungari. These learned people, regardless of ethnic or social status, identified as members of the Hungarian nation based on a legalistic-historical identification with the body of the realm.
 
I don’t think Hungarian really has a shot- if Hungary is the dominant kingdom/ location of monarchs main seat (which seems probable given its closest to the area that needs constant military attention), it has no need to get culturally defensive and switch from Latin to Magyar. The pod here is quite early, and things like the reformation could derail things, but the late adoption of Magyar in Hungary is not simply because the enlightenment and the vernacular revolution was late getting there, it’s because something different was going on with regards to the status of Latin in the national identity. Unlike other areas, where the vernacular was the language of the merchant class in Hungary, the language of cities was German, and Magyar was seen as the language of the nobility- famously not a group that is slow in switching languages.


But with a union beginning in 1504, I can imagine the west-slavicisation of the Hungarian elite by the 18th century, especially if Budapest is the capital. By the time of the enlightenment its not super implausible to me that any monarch who really really strongly feels that Latin has no place in a modern state would switch it out with west Slavic throughout the union, including Hungary.

I’m just gonna put some quotes from “Latin at the Crossroads of Identity: Linguistic Nationalism in the kingdom of Hungary”

Magyarization of Jagiellon realm is as likely as Gaelization of UK, it is pure fantasy. Polish/Czech, being Slavic, have massive advantage over Hungarian, which is not even Indo-European.
 
even in the beginning of Habsburg rule Bohemian parliament passed the law that every noble of Bohemia was supposed to know Czech
Isn't that a testament to Czech losing ground though? Or did Ferdinand specifically try to enforce German back then?
Poles conformed spelling of their words to Czech norm. And German was seen with suspicion in Poland.
Not in XVIth century, and than it depends on internal power balance in union later on. And well, once national language of Hungary is considered, Slovaks (once they would start having elites on their own) speak it and it would be easier to learn for Croatians for Hungarian, but I would say that is very hard to tell. Equally probably, Hungarian could prevail and we could have (in TTL's 19th century) magyarization being tried all over eastern Europe.
I have strong doubts about Hungarian being introduced as an official language anywhere besides Hungary itself and maybe Wallachia and Moldavia (if there's a very significant Hungarian migration to the area). From this perspective, Western Slavic becoming universally adopted is a hundred times more probable.
In Lithuania they didn't use Baltic Lithuanian in chancellory anyways, they used Old Ruthenian but usage of Polish among elites was common even before union, even those who opposed it (Radziwiłł family) written their letters to each other in Polish.
Yes, I remember us discussing that earlier in another thread. I wrote "maybe" only because I think the shift of the centre of power carries the possibility of instantenous Polonisation losing most of its incentives ITTL. Of course, I wrote this under the assumption that the usage of Latin would come to the forefront.
Polish was lingua franca of Eastern Europe in 17th century and was spoken even beyond PLC-it was used even at Russian court. Thus *Common West Slavic* could be even more widespread ITTL.
Interesting, I didn't know it was also used in Russia. Then if Czech and Polish literacies can synergise well and an intermediate dialect could develop, then that might just be able to become the language of the ruling classes through Europe East of Germany. I can't help but feel a bit sceptical, but I absolutely see the potential.
 
I don't think it's really telling something about losing ground or not and I wouldn't say Ferdinand tried to enforce German, but he definitely tried to promote it.
possibility
They didn't really think about it as polonisation, as I said even members of Radziwiłł family wrote their letters in Polish and they were most anti Poland and anti union
Magyarization of Jagiellon realm is as likely as Gaelization of UK, it is pure fantasy. Polish/Czech, being Slavic, have massive advantage over Hungarian, which is not even Indo-European.
Succesful magyarization yes, but if Hungary stays dominant in that union (depends on what happens with Poland and on whether Lithuania would keep its independence or not), I can see someone like Kossuth trying to pass a policy trying to spread Hungarian to other realms and probably it all ending up in massive rebellion in style of Croatia in 1848. Funnily enough, assuming "Common Western Slavic" emerges (very probable) the attempts on magyarization could strenghten shared Czech-Polish-Slovak identity because of sheer contrast between them and Hungarians. But it all depends on what exactly happens to Poland and Lithuania, if incorporation is succesful and Poland develops more sensible form of governance than after initial Magyar domination it becomes center of the union.
sceptical
Tho thats is exactly how I feel about it, it depends on few factors probably not decided in TTLs XVIth century (thus I am a bit sceptical as well) but overall I see the potential.
Thus *Common West Slavic* could be even more widespread ITTL.
Due to Czech element (IMHO Common Western Slavic could really resemble dialects spoken around Cieszyn area) I see it being easier to influence Eastern Slavs (phonetics would be a bit easier to adopt) and probably it would influence developmenf of Serbocroatian as well.
can imagine the west-slavicisation of the Hungarian elite by the 18th
As I said that depends on fate of Poland and Lithuania but assuming Poland develops as I wrote earlier to @Jan Olbracht than yes, tho if thats the case I would find it more probable that merchant class would switch from German to Common Western Slavic.
 
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