In a few days, the United Kingdom will hold a non-binding referendum, advising members of parliament either that the majority of voters would like to remain in the European Union, or that a majority would like to withdraw from it. Every party with more than one MP has a leader who is committed to remaining in the EU, and the classes to which MPs belong are dominated by economic interests which benefit from British membership in the EU. Therefore, unless Leave wins by a vast majority, as there is almost no chance it will do, the results are unlikely to precipitate British withdrawal from the EU. A win for Remain will lead to self-congratulation by advocates of British membership, to vows of continued resistance by opponents, and to no significant change. A win for Leave will probably trigger a leadership contest in the Conservative Party, the winner of which will be a prime minister who makes a great show of going to Brussels and presenting various demands for the European Union to reform its institutions. When those demands are either granted or politely taken under consideration, that prime minister will declare victory, claim to be a reincarnation of Alfred the Great (or more likely Winston Churchill, since historical literacy in the UK isn’t what it once was,) and go on with business as usual.
None of this is directly my business, as I do not live in the UK and am an American citizen. However, it does strike me that, throughout the history of the world, there have been many multinational federations. Some of these have labeled themselves as empires, famously including the Holy Roman Empire and the Dual Monarchy of the Hapsburgs; others as movements embodying a nationalism transcending borders that were dismissed as historical accidents, like the United Arab Republic under Nasser or Yugoslavia under Tito; some as the vanguard of global revolution, like the Soviet Union; etc. What they have in common is that their formal bureaucratic and legal structures were tolerable to the people of their member states as long as the underlying realities of economics and Realpolitik supported them. When economic circumstances and the power relations among the federation’s constituent parts shifted, those formal structures broke down and the federation itself ended. Since economic circumstances and power relations continually change, it is safe to assume that all multinational federations will sooner or later collapse, and that the primary distinction among them is between those that dissolve peacefully, like the Soviet Union or the United Arab Republic, and those that dissolve violently.
Among federations that dissolve violently, there is a second distinction to be drawn. Some dissolve as a consequence of wars they have fought and lost against outside states; others dissolve as a consequence of wars among nations within the federation. Outside states usually involve themselves in these internal wars as sponsors of the various sides.
If the current goings-on in the UK are any indication, it seems unlikely that the European Union will dissolve peacefully. How might a violent dissolution of the EU play out? The principal geopolitical division in Europe is between the Western section, naturally dominated by Germany, and the Eastern section, naturally dominated by Russia. When the European Economic Community and NATO were formed, Germany was divided, defeated, and occupied, as weak as it could be, while Russia was the nucleus of the USSR, an empire of nearly unlimited reach. These institutions then served to sustain a balance of power between the two halves of Europe. Now, Germany is the undisputed mistress of western Europe, while Russia is still isolated and relatively impoverished. Under these conditions, a set of institutions that commit the United States of America and the members of the EU to a perpetual alliance with Germany against Russia can serve only to unbalance the European system and make general war more likely. Every time in history when Germany has been strong and Russia is weak, the Germans have grown reckless pressing their claims in the East, ultimately provoking the Russians to war. There is little reason to suppose that matters will play out any differently this time.
If Russia undergoes an economic and political resurgence soon enough, then perhaps Russia will be able to contain Germany’s ambitions before they take the situation to its usual cataclysmic outcome. If that resurgence continues long enough, and is accompanied by a relative decline in Germany’s fortunes, perhaps the European Union will end as Yugoslavia ended. As Germany sponsored Croatia and other states in their anti-Serbian efforts leading to the destruction of Yugoslavia while the powerless Russia of the 1990s looked on, so in the future Russia might sponsor anti-German efforts on the part of various EU member states, leading to the destruction of the EU while a weakened USA looks on from across the ocean. This scenario would be as likely as an outright war between Germany and Russia to involve a large-scale thermonuclear exchange and therefore the destruction of civilization.
Of course, simply because the UK is going through rather an unfortunate bit of political theater right now does not mean that it will not be possible, at some future date, for the members of the European Union to escape peacefully. It might be more difficult than one supposes, however. A German government unrestrained by the need to maintain a coalition that includes the Social Democrats might very well charge hard enough into the former Soviet republics, pressing NATO membership for Ukraine and Georgia for example, that there might not be time for a peaceful breakup. If the USA is led by so hawkish an administration as that which Hillary Clinton has promised to conduct, then such a danger would be very close by.
If that danger is avoided, there would likely be some warning before EU member states erupt in civil war. One would like to suppose that member states would withdraw peacefully rather than fight civil wars to postpone departure. What might prevent peaceful dissolution would be a sharp cleavage in economic interests between social classes in the member states. Should a time come when it is clearly not in the interest of most people in certain EU member states to continue in the federation, while it was as clearly in the interest of the elites in those states to continue, then civil wars on the Yugoslav model would be very close at hand.