Did Europe Really Learn to Live in Peace, or Did America Keep the Peace?

Did Europe Learn to Live in Peace?

There is something extraordinary about Europe that we hardly notice anymore. For more than eighty years, France and Germany have not fought each other. Neither have Germany and Poland, France and Britain, or any of Western Europe’s major powers.

That does not mean Europe has enjoyed eighty years of peace. It hasn’t. We had the wars in Yugoslavia and Kosovo, and today there is a brutal war in Ukraine. What is extraordinary is something else: for centuries, Europe’s great powers regularly settled their differences through war, and after 1945 they stopped doing so.

We Europeans have a rather comforting explanation for this. We learned. After two world wars, we finally understood where nationalism could lead us. France and Germany reconciled, economies became intertwined, common institutions were built and eventually we created the European Union.

All of that is true. But something else happened after 1945 that tends to receive less attention: the Americans stayed.

This is where an uncomfortable historical comparison becomes interesting. Not because the United States is Rome or because postwar Europe became an American province. That would be absurd. But there is something about the function of the Pax Romana that deserves a second look.

Rome did not magically transform Gauls, Iberians, Greeks or Germans into beings of light. Their identities, interests and rivalries did not disappear. What Rome created was a larger order capable of keeping many of those rivalries within limits.

So perhaps, separated by two thousand years of history, we should ask a similar question about Europe after 1945. Did Europeans stop fighting because we finally changed, or did we also change because a new political and military architecture made fighting each other much more difficult?

It is not just a provocative historical analogy. NATO itself, when describing the reasons for its creation, lists three original purposes: deterring Soviet expansionism, encouraging European political integration and preventing the revival of nationalist militarism in Europe through a strong North American presence.

That last point is easily forgotten. The people who designed the postwar system did not behave as if European nationalism had suddenly disappeared. They had seen too much to believe that Germans, Frenchmen, Poles and Britons had somehow become the children of light.

The United States placed a military and nuclear umbrella over Western Europe. Germany could rebuild without every new German factory being immediately interpreted as the beginning of another threat. France maintained its independence and eventually developed its own nuclear deterrent. Britain did the same. Former enemies found themselves inside the same military alliance, while a power far greater than any of them stood behind the entire system.

The arrangement worked remarkably well. Perhaps too well, because over time we began to confuse controlling a problem with eliminating it.

Europe was free to concentrate on trade, production, prosperity and integration. We could spend months arguing about deficits, agricultural subsidies, tomatoes and olives without seriously wondering how many divisions the country next door had. That was not a minor achievement. It was one of the greatest political transformations in European history.

But nationalism did not disappear, and neither did nations. Germany remained Germany, France remained France and Poland remained Poland. What changed was the environment in which those countries pursued their interests.

That environment is now beginning to change.

The United States has not abandoned Europe. It still has roughly 80,000 military personnel on the continent and remains the central military power inside NATO. The American policeman is still on the corner, but he is increasingly telling the neighbors that they will have to take much greater responsibility for looking after their own street.

Europe has heard the message, and nowhere is the change more striking than in Germany.

Berlin is spending roughly €108 billion on defense in 2026 through its regular defense budget and the Bundeswehr special fund, with spending planned to rise sharply again in 2027. Chancellor Friedrich Merz has also been unusually clear about the objective: Germany wants the Bundeswehr to become Europe’s strongest conventional army.

Twenty years ago, hearing a German chancellor say something like that would have caused a certain amount of unease in several European capitals. Today it sounds almost normal, and there are perfectly understandable reasons why.

Russia invaded Ukraine. War returned to Europe. Washington wants Europeans to carry a much larger share of their own defense. Germany has also discovered that a significant part of its prosperity rested on an extraordinarily comfortable combination: American security, cheap Russian energy and expanding trade with China.

That combination no longer exists, and Europe is now trying to build something to replace it.

This is where the question becomes more complicated than simply whether Europe should spend more on defense. Germany may become Europe’s dominant conventional military power, but it has no nuclear weapons. France does. Britain does too, although Britain is no longer a member of the European Union. Poland, meanwhile, is rearming rapidly while looking east toward Russia and remembering its own history very well.

A question that seemed safely buried in European history books therefore begins to return: how will power be organized inside Europe if the United States gradually becomes less central to European security?

There is no reason why the answer has to be a return to the old balance-of-power politics. Europe can integrate its defense more deeply, and there are already signs that this is happening. France and Germany have moved toward closer strategic coordination, including discussions touching on France’s nuclear deterrent. A more powerful German military could therefore strengthen a common European structure rather than undermine it.

But the distinction matters. It is one thing for France to look at more German tanks and see more tanks defending Europe. It would be something very different for France to start counting those tanks simply because they are German.

That does not mean we should start imagining another Franco-German war. That would be ridiculous. The mechanism is far more subtle. States calculate power and security, even when they are friends. If the larger structure around them weakens enough, governments begin asking what their neighbors have, what they themselves need, who would come to their aid and what might happen if circumstances changed.

Nobody has to want a war for those calculations to return.

This is why perhaps we Europeans should be a little less self-congratulatory when explaining the last eighty years. Franco-German reconciliation was real. European integration was real. The European Union is a historic achievement. European democracies built a network of common interests that our grandparents would have found almost unimaginable.

But there was also a policeman on the corner, and he was American.

For decades, his presence allowed Germans, Frenchmen, Italians, Poles and Britons to think much less about their security in relation to one another. Europe could build economic and political integration while a large part of the strategic problem was handled within an American-led security system.

Today we speak increasingly about European strategic autonomy. Perhaps that is both necessary and inevitable. But autonomy means more than spending additional billions on weapons and enlarging national armies. It means building a European security architecture capable of taking over functions that, for eighty years, were performed to a considerable extent by the United States.

And this brings us back to Rome.

The Pax Romana did not erase the identities of the peoples living within it, nor did it eliminate their interests or rivalries. What it did, for a remarkably long time, was place many of them inside a larger order. When that order weakened, things that had seemed to matter much less began to matter again.

The European Pax Americana has not ended. It may not even be ending. But for the first time in decades, it is possible to seriously imagine a Europe in which the United States plays a much smaller role in maintaining European security.

Perhaps Europe really did learn from its history. Perhaps eighty years of integration have changed the relationship between European nations so profoundly that the old rivalries really do belong in museums and history books.

I hope so.

But there is another possibility worth considering. Perhaps we have told ourselves a story that is simply too comfortable: that after centuries of killing one another, Europeans finally understood their mistakes, left their nationalisms behind and became the children of light.

Two thousand years of European history suggest that we should be a little more cautious.

The real question may not be whether Europe can defend itself without the United States. It may be whether Europe can remain the Europe we have known for the last eighty years when there is no longer an American sitting at the head of the table.