What happened Wednesday did not trigger an Asia-wide superpower war. Not quite.

When the United States deliberately flew two B-52 bombers over a group of contested islands between China and Japan to protest China's seizure of airspace above the islands, Beijing decided not to scramble fighter jets to meet them  – though it did, on Friday, against Japan, but without firing any shots. After all, neither Chinese President Xi Jinping nor his U.S. or Japanese counterparts claim to be interested in having a war. It would be profoundly against all their economic and political interests.

But it still worries us, because we know that the Pentagon and China's military both have detailed plans drawn up for full-scale wars against one another. Could a future incident like this set those plans in motion? "The chances of a real war are still low," China analyst Cheng Li of the Brookings Institution told The New York Times after the incident. "But sometimes incidents will push leaders into a corner."

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Likewise, what happened last Sunday was not the world pulling back from the brink of a Middle East-wide war of mutual annihilation. Not quite. The decision by Iran, the United States and its allies to strike an interim deal toward limiting Iran's nuclear program did, at least temporarily, end the possibility of an Israeli attack on Iran. Such an attack, supposedly limited and surgical, would almost certainly provoke a far wider and perhaps endless conflagration. By shifting a military standoff into a diplomatic confrontation, this became a political matter rather than a cause for war.

We worry, though, because the Iranian and Israeli militaries and political hawks have their own minds, and their own plans, and those plans might be triggered by figures outside the diplomatic and political loop.

Between these incidents, we find one of the questions of our day: Even though the world is politically at peace, is it possible for our militaries to drag us into war?

That question has deep historical resonance. We used to think that wars were triggered by heated tribal animosities, by the hubris of madmen, by struggles for resources or by powerful economic forces. None of these ideas have been much use in explaining the wars of the past century. All of them were swept away, during my student years, by the new concept formulated by British historian A.J.P. Taylor: the "timetable theory."

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Studying the First World War, Mr. Taylor found that none of Europe's political leaders had sought a larger war, nor did it serve any of their national interests to enter one. But their huge military bureaucracies had drawn elaborate, clockwork plans to mobilize millions of soldiers on multiple fronts at short notice, and a minor confrontation in Bosnia set all these plans in motion on a continental scale.

This theory is given its ultimate test in Margaret MacMillan's new book The War That Ended Peace: The Road to 1914, in which the Oxford University historian provides a definitive (and gripping) examination of the factors that led Europe into 30 years of largely unnecessary war. The timetable theory remains important though not crucial to her interpretation, but Dr. MacMillan adds a new dimension.

The danger, she finds, is a military that sees itself as autonomous from the country's political leadership and civil service, combined with political leaders who are weak, self-interested or too eager to acquiesce to the military's demands.

"Over the decades, and not just in Germany," she writes, "both military and civilian leaders had come to accept that military planning was the business of the experts and that civilians had neither the knowledge nor the authority to ask searching questions or dispute their decisions … Such attitudes were dangerous because the two spheres, military and civil, and the two activities, peace and war, could not be so neatly divided; the general staff was to make decisions on military grounds – famously the decision to invade Belgium in 1914 – which were to have serious political implications."

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Today, we live in a different world. Militarized societies and elaborate honour codes have vanished from the West. The lessons of the Great War have, in theory, been learned.

Yet the risk of a timetable war, or something like it, remains real. Limited-scope military actions have turned into decade-long wars in Vietnam and Iraq because of this phenomenon.

We saw this with Canada in Afghanistan, when what should have been a one- or two-year strike against al-Qaeda turned into a decade-long debacle because the military depended on a counterinsurgency plan that would have required decades and tens of thousands of soldiers, and had no tangible plan for its own failure. For the better part of a decade, political leaders (of both governing parties) were too willing to acquiesce to a military schedule whose outcomes were unobtainable.

Politicians and diplomats have been able to intervene to gain control over such military-led agendas. This is what Henry Kissinger did by launching the U.S. détente policies toward China in the 1970s, and what George Schultz attempted with the Soviet Union in the 1980s, turning a military standoff, driven by nuclear-armed schedules and agendas, into a diplomatic confrontation, driven by summits and negotiations. It was imperfect, as schedule-driven forces continued to dominate the militaries of both countries, but it prevented war. This is, in turn, what Barack Obama and John Kerry did this week with Iran: a shift of the centre of confrontation from the military into the diplomatic sphere. The risk of Iran, Israel or the United States triggering a "limited action" that spirals into a greater war is now considerably reduced.

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This is an age of peace  – there are fewer wars, or people affected by war, than at any previous time in human history   –  but also an age of brinkmanship and military independence. A century ago, that very combination took us over the brink.

Follow me on Twitter: @DougSaunders