In every year of the two generations that followed the treaty of Cateau-Cambrésis in 1559 European soldiers were somewhere engaged in battle, skirmish or siege. Few of these actions were on a large scale and none of them was decisive. Christian fought Turk and Catholic power fought Protestant by land and sea; France was distracted by civil wars for thirty years, the Netherlands for forty. Yet when the fighting petered out, the frontiers ran as geography, economic vitality, religion and patriotism dictated, not in patterns cut out by the sword. The costs of war continued to grow, and the sums raised were never enough to release into effectiveness the tactical lessons or the technical advances of the previous period, let alone the flood of advice offered by a new race of military experts. The need for regular pay, increased professionalism and something like a permanent establishment was recognised, but little was done about it. Ambitious plans laid at home were passed to the front in sieves of peculation and inefficiency. It was not a period of achievement, it was not in any real sense a period of transition, yet in no previous age had war loomed so large in men's lives and, through the pulpit, the stage, the fine arts and the press, in their imaginations.

The recurrence of wars was taken for granted. ‘To speak of peace perpetual in this world of contention’, wrote Thomas Digges, ‘is but as Aristotles foelix, Xenophons Cyrus, Quintilians Orator, or Sir Thomas Moores Utopia, a matter of mere contemplation, the warre being in this iron age si bien enracinée qu'il est impossible de l'en oster, si non avec la ruine de l'universe’. But if there was less pacifism than in the first half of the century, there was a greater self-consciousness about the legitimacy of war as such, and a more widespread urge to explain the difference between a just and an unjust war.