In the years after the First World War, the British Foreign Office included a position of Historical Adviser. In the 1920s the incumbent was one Sir James Headlam-Morley, a man with the only proper training for an expert in almost any field of human endeavor, but especially for the conduct of foreign policy and diplomacy: I mean, of course, Classical Studies. In the early 1920s he wrote some papers advising his masters on current policy, guided by his historical studies. Their shrewdness and wisdom, and the accuracy of their analysis are astonishing.

In January 1922 he wrote a paper entitled “The Guarantee Treaties, 1814/15–1919,” comparing the situation in 1919 to that after the Napoleonic wars. The comparison seemed to him apt. Concern for France’s “revolutionary doctrines” in 1815 existed, as did concern about “German militarism” in 1919. Europe had needed a guarantee against a new aggression by France just as it needed protection from “a fresh outburst of German militarism.” Germany and Belgium needed guarantees of security in the earlier period as France did in the later. After 1814 the British made treaties with continental powers guaranteeing Europe against renewed French aggression, and they worked: “It was this policy—the continuance of the alliance as a potential weapon which, at any moment might become operative—by which, in fact, the peace of Europe was maintained, and the key to the whole system was the participation of Great Britain.” By analogy, a treaty guaranteeing France against German aggression in 1922