As in 1898, we had prepared for war in time of peace, and we were willing to fight a war because we were so well prepared for it. Certainly few could doubt that we were ready. We faced no shortage of manpower; a peacetime draft was the law of the land, even though such a thing was virtually unheard of in our history.

We had always had our arsenals and military bases, but now entire industries came to rely on Pentagon appropriations, along with important sections of the country. The aerospace industry fattened on those dollars, and as it grew, so did Southern California, its principal center. The South also benefited; its culture was strongly patriotic and pro-military to begin with, and it had the advantage of a host of powerful senior representatives and senators. The folks back home appreciated their work. They repeatedly re-elected such barons as Congressman Mendel Rivers, who brought home the bacon and then ran in the election under the slogan “Rivers Delivers.”

It was no new thing for a powerful force to stand at the ready, preparing for a war that it might never fight. Between the two world wars, for instance, our battleships spent most of their time in harbor as their crews chipped rust. But the Cold War was different; it put a strong emphasis on preparedness, and now there was enough money around to put real muscle into this policy. Fleets of bombers stood on alert, with part of the force remaining airborne at all times. Naval skippers vied to spend time at sea. Army divisions carried out maneuvers and exercises, including in time the annual Reforger operation, in which a powerful force would fly to Germany, match up with pre-positioned tanks and other equipment, and then go tearing around the countryside. Even the divisiveness of Vietnam did little to change this state of affairs. There was every reason to think it would go on ndefinitely.

On an evening in August 1914, as the British cabinet prepared for war, Sir Edward Grey, the foreign minister, stood with a friend in Whitehall and watched through a window as the lamplighters made their rounds. “The lamps are going out all over Europe,” he said. “We shall not see them lit again in our lifetime.”

The war Grey saw gathering was every bit as fearsome as his worst imaginings could have made it, and its unprecedented destruction led to a punitive peace, a greater war, and a three-quarters-century struggle to maintain a Marxist state in Europe. Grey was right; a baby born that evening would have been seventy-five years old before the lights came on again. But in 1989 the lamps did come on, as communist dictatorships collapsed throughout Eastern Europe and the Berlin Wall came down. During the next two years communism fell within the Soviet Union itself. Russia re-emerged, under its czarist flag and with borders astonishingly close to those of three centuries earlier. Almost as suddenly as in 1949, the world’s tectonic plates shifted; the basis for our policy disappeared. It was not true, after all, that the East-West struggle would hold an endemic and centuries-long character. Seventy-five years of war and threat of war were at an end; as in 1815, the world could look forward to a long peace.

Now, amid the early stirrings of this peace, we feel anew the old urge not to maintain large standing armies or extensive military establishments. As recently as 1986, at the peak of President Reagan’s build-up, the Pentagon took 6.5 percent of our gross national product. Within the present decade the percentage may fall to half of this. And as we look ahead to a prolonged era of peace, we ask again the old questions: What sort of military force should we support? What, finally, do we need?

In addressing these issues, a useful point of departure lies in noting that the greatest danger of war lies where volatile nationalism erupts within a region that is central to our interests. The Middle East represents the clearest example of such a region. For as far into the future as we can see, we must anticipate that America, Japan, and Europe all will rely on its oil.

This combination, joining volatility with vital interest, provides a historical context for the 1991 Gulf War. And that war offers more, for it stands as an example of the “nth-country problem”: In a world where the major powers all work for peace, a small nation, such as Iraq, may gain a wholly disproportionate level of importance by wielding military force that others are unwilling to counter.

Additional danger of American involvement may arise from local conflicts, such as the present civil war in Bosnia. Such small-scale wars do not directly engage our national interest. But they can powerfully engage the widespread belief that our nation is special, that we have a historical mission, and that we must intervene to lead the world to justice and right. This strain of militant idealism runs deep; President Wilson drew on it in 1917, and certainly we have not seen the last of his successors.

Short of outright war or intervention, our force levels will also show the influence of deterrence, of policies that can maintain an armed peace. Here too we may see new initiatives, and these could reflect a third theme: the desire of economically strong powers to build a commensurate military strength. The outstanding potential example is Japan.