The year 2014 will be remembered as a transitional year in the political climate of Europe. Following the civil war in eastern Ukraine and the incorporation of Crimea by the Russian Federation, the continent is experiencing a reversal from a system of consensus into a system that is more reminiscent of the past opposition between NATO and the Warsaw Pact. This shift may seem even more surprising, because the new order that had rapidly emerged after the end of the cold war, with its regular conferences and summits, had become the order of the day. Unfortunately, international relations do not follow a uniform path of progress; there is, of course, no "end to history".
There were also highlights in the past. In particular, the experience of the Congress of Vienna after the fall of Napoleon Bonaparte was a watershed in international relations. Its bicentenary in 2014-15 is a useful opportunity to reflect on a question that has come back to the fore with the current crisis in Ukraine; when strong differences arise between two or more powers, what is the most effective and least costly way to resolve them? In the absence of effective international arbitration, three methods have been traditionally used: war (as a judicial duel), the balance of power (two military blocs that mutually neutralize each other, by fear of an open conflict), and conference diplomacy. All three were applied in Europe in the post-Napoleonic era and in that order.
The first one was war. Napoleon engaged in his own campaigns of invasion deliberately, and with cold-blooded determination. For him, as Carl von Clausewitz would later write: "War is an act of violence intended to compel the opponent to fulfill one's will". Undoubtedly, the Emperor of the French used this form of argumentation effectively against two of the great powers of the time, Austria and Prussia: with two fast campaigns in 1805 and 1806, he decisively defeated the first, and effaced the second from the map. Applying the principle that "might makes right", he obtained satisfaction for all his claims, including the hand of the daughter of the Emperor of Austria.
War is, however, a risky affair and it tends to attract retribution. Napoleon's campaigns were costly both in human and economic terms for France, and for Europe in general. Most of all, his invasion of Russia ended in a dismal debacle, and was followed by a lightning-fast Russian counteroffensive into the heart of Germany, culminating in the Battle...