What Unites East Central Europe?

From From Peoples into Nations: A History of Eastern Europe, by John Connelly (Princeton University Press, 2020), Kindle pp. 3-4:

What unites this dramatic and unsettling history is a band of countries that runs from the Baltic Sea down to the Adriatic and Black Seas, between the much larger, historically imperial Russia and Turkey in the east, and Prussian and Austrian Germany in the west. These small countries constitute East Central Europe, a space where more of the twentieth century happened—for good and for bad—than anywhere else on the planet.

If one seeks a simple explanation for the energies that caused this area to produce so much drama and so many new concepts, a glance at the map suggests nationalism: no other region has witnessed such frequent, radical, and violent changing of borders to make nations fit states. Two maps, one from 1800, one from 2000, tell the basic story: a shift from simplicity to complexity, from one small and three large multinational powers to more than twenty national states.

The story was carried forward by the demands of East European nationalists to control territory, demands that triggered resistance, because they contested imperial power and the European order. Since the 1820s, the work of nationalists has brought independent states into being in three stages: the first in 1878, when the Congress of Berlin produced Serbia, Romania, Bulgaria, and Montenegro; the second, in 1919, when revolution and peace making generated Czechoslovakia, Yugoslavia, and Poland; and most recently, in the 1990s, when Czechoslovakia broke peacefully into the Czech Republic and Slovakia, and Yugoslavia fragmented violently into Slovenia, Croatia, Serbia, two entities in Bosnia, Macedonia, Montenegro, and Kosovo. Hungary became de facto independent in 1867, when the Austrian Empire divided into Austria-Hungary; after 1920, it emerged much reduced from World War I, two-thirds of its territory going to its neighbors.

What can be debated is whether the degree of violence, especially in World War I, was necessary to break loose the nation-states that now constitute the map of Eastern Europe. Austria-Hungary was more resilient than critics gave it credit for and only began unraveling in the final year of a war that had been costly beyond any expectations. And there was little relation between intention and outcome: World War I did not begin as a war of national liberation. Yet by 1917, as the causality lists soared and any relation between intention and outcome was lost, it was interpreted to be one. It was a war for democracy—for Wilson’s national self-determination—and that helped spawn the new nation-states.

At the same time, without the cause Gavrilo Princip claimed to represent (that South Slavs should live in one state), there would have been no assassination, no Habsburg ultimatum to Serbia (which had trained Princip and supplied him with his pistol) in July 1914, and no war. Seen in rational terms, the Habsburgs’ belief that Serbia, a state of three million, represented a challenge requiring a full-scale military assault launched from their state of fifty-two million, seems one of history’s great overreactions. But Princip, the frail eighteen-year-old rejected from the Serb army for his small stature, embodied the challenge of an idea, the idea of ethnic nationalism, and the Habsburg monarchy had no response other than naked force.