A professor of mine once told me that his worst lectures were on topics he knew most about. He got lost in the details. He gave his most successful lectures when, as a young assistant professor, he was assigned to teach European history from the fall of the Roman Empire to 1945! That's by way of a caveat. I'm afraid that I will be less than lucid because I know too much about this period, but I'll try my best.
The multi-national character of the Kingdom of Hungary didn't pose serious problems until the early nineteenth century when modern nationalism reached the area. The first nationality group to get the bug was the Hungarian. The leading politicians of the Era of Reform, besides demanding modernization and striving for democratic changes, also pushed for more and more rights for the Hungarian nation within the Habsburg Empire. Although the 1848-49 revolution didn't start off as a war of independence, it ended as such.
Within the Kingdom of Hungary other national groups–Croats, Slovaks, and Romanians–although lagging somewhat chronologically, were also affected by nationalism. Hungarian nationalism was directed against Austria, while the non-Hungarians' demands could only have been satisfied at the expense of the Hungarians who believed that they were the sole group within the country with the ability for "state building." And if it depended on them, the Hungarian political elite would have preferred an independent Hungary territorially intact.
The problem with these goals was that independence and territorial integrity were incompatible. This was something most Hungarians refused to acknowledge, although the problem became quite apparent already during the 1848-49 revolutionary period when nationality conflicts within the country came to the surface. It is very possible that if Hungary had managed to win against the Austrian and Russian forces in 1849 and had thus been able to achieve the much desired goal of independence, soon enough it would have fallen apart under its own weight. At this point the Hungarians were a minority in the Kingdom of Hungary.
The Compromise of 1867 (the dual monarchy in which Hungary achieved home rule) was the best deal Hungary could have gotten from Vienna. But over the next fifty years Hungarian politics still centered around Hungary's relations with Vienna. In fact, there was even a Party of Independence that at least on paper strove for total independence. While the constitutional struggle between the Hungarians and the Crown was taking place, the nationality situation was becoming a serious issue. In 1868 the Hungarian parliament enacted a very enlightened nationality law; the problem was that in practice it was blissfully ignored. Meanwhile the number of Hungarian speakers was growing steadily. The magic 50% level was reached by 1900; in 1910, at the time of the last census on the basis of which decisions in Paris were reached, it was 54.4%.
Although there were attempts to forcibly assimilate non-Hungarians, my opinion is that most of the increase in Hungarian speakers came as a result of economic growth and, with it, urbanization. For example, about 300,000 Slovaks moved to Budapest seeking work in the bustling capital. But one didn't have to go that far in order to become assimilated in a generation or so. Bigger cities in today's Slovakia (then called the Uplands) were also places where a change of nationality took place on a massive scale. The assimilation of Romanians was sluggish, partly because of religious differences and a very high birth rate.
So, what could the Hungarian ruling classes do under these circumstances if they wanted to keep their country intact? The majority of the people simply refused to face the problem. Moreover, they were convinced that the nationalities had no legitimate grounds for complaint. They refused to consider the existence of any discrimination against non-Hungarians. According to these people everything was just fine as it was. They figured that with the passing of time more and more non-Hungarians would have a burning desire to become Hungarians because, after all, being a Hungarian was decidedly better than being a Slovak or a Romanian. Sooner or later the Hungarians would have a large majority and all would be well.
There were very few people, really just a handful, like Oszkár Jászi, who thought that some kind of understanding with the nationalities was necessary. What he had in mind was "cultural autonomy" for the nationalities, very much along the lines of Otto Bauer's ideas. The Hungarian ruling class condemned Jászi. He was considered to be a traitor who was enabling the demise of historic Hungary. Jászi, of course, was sure that his ideas, once implemented, would help to preserve the country's territorial integrity.
I hate to be skeptical, but in my opinion neither the conservatives' assimilation policy nor Jászi's ideas of cultural autonomy could have saved historic Hungary. Sooner or later the desire of the nationalities to have their own independent states or join their fellow Romanians or Serbs outside of Hungary's borders would have resulted in some kind of Trianon. Perhaps a peaceful Trianon, but it would have been the end of Greater Hungary. There are examples elsewhere in the region. For instance, in the last few years we have witnessed the dissolution of the neighboring multi-national Yugoslavia where it seemed that the nationalities lived side by side in harmony for fifty years. Or consider the states that were formed after the collapse of the Russian/Soviet empires.
Of course, it would have been better from the Hungarian point of view if the collapse had come as late as possible and not after a lost war. If it had been a negotiated settlement between Hungarians and their non-Hungarian-speaking fellow citizens. Unfortunately, the end came after a lost war and the terms were not negotiated.
But once it happened, what would have been the best tactic for a much smaller Hungary with large Hungarian minorities in three countries: Czechoslovakia, Romania, and Yugoslavia? This is the question we have to pose and perhaps try to answer tomorrow.