Historians have commonly taken the secularization of politics and diplomacy as one of the great themes of the seventeenth century, and rightly so. But secular attitudes in matters of state did not move in an unbroken, irresistible progression; until well into the century they coexisted with more traditional modes of thought and developed against resistance from many people who still believed it immoral to divorce religion from politics. Moreover it was by no means always clear which trend was the stronger. Thus long after the Peace of Westphalia, for example, the possibility of international religious war continued to seem real, even to the point where fears of it entered into considerations of diplomacy. One interesting case of this kind arose in the course of Anglo-French negotiations during the mid-1650s, when apprehension of a Catholic crusade on the one side and rumors of a Protestant one on the other added a special dimension to an already complicated situation.
