The much anticipated Becker-Posner Blog, an exchange between intellectual giants (a federal judge and a Nobel Prize winning economist), has begun with a topic that is (hopefully) no longer timely: when pre-emptive and preventive war are justified and should be used (here and here).

Dr. Posner contributed a cost analysis. He ends with this example of when nations should have fought to end a future threat:

A historical example that illustrates this analysis is the Nazi reoccupation of the Rhineland area of Germany in 1936, an area that had been demilitarized by the Treaty of Versailles. Had France and Great Britain responded to this treaty violation by invading Germany, in all likelihood Hitler would have been overthrown and World War II averted.

On the surface, this may not seem controversial. We know from William Shirer’s Berlin Diary that the German army was not prepared to encounter opposition. The force sent in to remilitarize was small and lightly armed. Had the Entente powers responded to their actions, the German army would have beat its way back to the right river.

Would the failure of remilitarization have led to a coup d’etat against Hitler (or some other means by which he would be removed from power)? This is a stretch. If we assume that Dr. Posner was speaking emphatically, that he meant that Hitler would have been politically weakened, it is a stretch. Much of it would depend on the constellation of powers that opposed and, necessarily, reoccupied the Rhineland in 1936.

Dr. Posner points to two powers whose opposition could have contained German power in 1936: Britain and France. (Although the United States was not a signer to the Locarno Pact, it could have participated as well.) But it was unlikely that both power would be involved. British government was far less willing than France to undertake an invasion and reoccupation, something which did not bode well for the enterprise, and the British public did not oppose the rearmament. Unfortunately, as Adenauer noted as early as 1919, everything depended on Britain: Wenn England das Ausweg als einen solchen bezeichnet, wird es ein Ausweg werden.

France could have expelled the German army on its own. It was strong enough, but it was unwilling to risk a war on its own soil without British participation. French policy was to push the theater of war into Eastern Europe if possible (a reaction to the memories of trench warfare). Nonetheless, unilateral action by France would have been viewed by the German people through the lens of the history of warfare between the two nations. It would be another conflict with an ancestral enemy.

The success of a France-only occupation can be gauged by the occupation of the Rhineland following World War One and the brief occupation of the Ruhr in 1923-4. Their presence in the Palatinate was extremely unpopular. Germans believed that France was trying to rend Germany apart in order to create a buffer state (a charge that is not without merit and which is constantly debated). They policed the political activities of the people and tossed out bureaucrats and replaced them with people who were more loyal. They tried to turn the Rhine into a French economic zone. They gave tepid support to separatists: not enough that the separatists would succeed, but enough to make it clear that the French army was creating disorder within the Palatinate. The exit of the French occupying forces was met with great celebrations, and those who collaborated with the French suffered from violent reprisals and public humiliation. The reaction of Germans to the French presence could have been worse: the participation of other nations, particularly Britain, made the occupation tolerable.

Because of the unpopularity of France among Germans, Rhinelanders in particular, it is possible that a reoccupation of the Rhineland would have strengthened Hitler (politically if not militarily). The Rhine was an area that supported Hitler less than others, but there was lingering resentment over the French occupation. As Heinrich Böll noted in his memoirs, Rhinelanders were overjoyed at the reoccupation: not because it was a success for Hitler, but because it ended more than a decade of helplessness and uncertainty.

Given the resentment that Rhinelanders had for France, it is natural to ask some questions. How would they have reacted to a reoccupation? Would there be resistance (passive resistance succeeded in forcing the French to leave the Ruhr Valley in 1924)? Would resistance have become violent? Would not the French presence played into Hitler’s vitriol against the international community that kept Germany from being a world power?

This is not to say that France (and Britain) should not have opposed the remilitarization of the Rhineland. The circumstances suggested a real threat to France … something more than just a violation of the Locarno Pact. What neither should have predicted is that opposing the remilitarization would be anything but messy. Dr. Posner did not need to add to his historical example that Hitler would have been overthrown: it was strong enough without it. His historical example is not very historical: it is a reinterpretation of history based on his rhetorical argument. And the question of pre-emptive and preventive war could have used more historical analysis.