Some years ago, I was fortunate enough to attend a small dinner at which the guest of honor was someone who, in my estimation, had quietly served America well in substantial foreign and economic policy positions for over two decades. During a conversational lull, I asked this gentleman what he regarded as America’s biggest foreign policy miscalculation in the twentieth century. Expecting him to say “Vietnam” or “The Bay of Pigs,” I was taken aback when he stated, “That’s easy: France, 1940.”

He was of course referring to the abrupt collapse of France under the impetus of the German offensive of May 1940, in which Hitler’s Wehrmacht achieved in six weeks what the Kaiser’s army couldn’t in four years. But, I thought, wasn’t France’s surrender far more consequential for Britain than America? Over time, however, I’ve come to see the wisdom of my interlocutor’s comment. The Armistice signed by France on June 22, 1940, the Third Republic’s subsequent self-dissolution, and the establishment of L’état française (better known as Vichy France) under Marshal Philippe Pétain left Britain alone and dreadfully exposed. Yet the same events instantaneously discredited some vital American working assumptions about European and global politics. Even worse, America’s foreign policy establishment never saw it coming.

Exploring how this happened, America’s reaction to France’s fall, and the postwar consequences is the subject of Michael S. Neiberg’s When France Fell: The Vichy Crisis and the Fate of the Anglo-American Alliance. A well-written and sourced book, Neiberg provides fascinating insights into the thoughts, actions, and blind-spots of figures ranging from generals like Mark Clark and Dwight Eisenhower to America’s longest-serving Secretary of State, Cordell Hull, as they grappled with a situation they never anticipated.

The Long Fall

According to Neiberg, the strategic supposition upon which America operated in the late-1930s as Nazi Germany’s geopolitical ambitions become harder to deny was that France—a World War I victor with a large colonial empire, state-of-the-art navy, and, above all, what was considered the world’s strongest army—would form a bulwark with Britain’s assistance against German aggression. That, it was thought, would give the United States time to prepare public opinion and re-arm so that something similar to the triumphs of 1918 would unfold. May 1940 threw that particular calculation into the bin of irrelevancy.

For decades, many have argued that American policymakers should have recognized that France simply was not the power it once was, and planned accordingly. Hindsight, however, is a wonderful thing. In the 1930s, few doubted that France would continue to play the prominent role which it had occupied in international politics since the mid-seventeenth century. It wasn’t for trivial reasons that French was the international language from the early-1700s until the 1960s. Between roughly 1665 and the mid-nineteenth century, France was the power around which European and arguably global politics largely pivoted. Its population size, large economy, talented soldiers and administrators, powerful military, formidable leaders like Louis XIV and Napoleon, and hegemonic drive underpinned first by Catholic absolutism and dynastic ambition, then Revolutionary fervor, and finally the idea that France had a unique civilizational destiny—la mission civilisatrice—meant that France was the country to which everyone else found themselves reacting.

That background, plus the fact that France had prevailed in the struggle against Imperial Germany in World War I, blinded many to some important realities that began looming into view from the 1850s onwards. One was economic. France’s economy was eclipsed first by Britain, followed by America and a unified Germany. Another reality was demographic. The populations of Germany, Britain, and Russia grew throughout the nineteenth century while France’s birthrate lagged behind and fell. At the end of World War I, France had a population of 40 million compared to Germany’s 70 million. At a time of universal conscription and mass armies, this put the French at a permanent military disadvantage and made it highly reliant on allies. Then there was the deep internal fracture between the two Frances—Catholic royalist France and Voltarian republican France—that had politically shattered the country during the Dreyfus Affair in the 1890s and 1900s and still influenced French politics and culture as late as 1940. Overlaying this was the rise inside France of one of the world’s biggest Communist parties: a political movement which effectively formed a state-within-a-state and was notorious for its slavish obedience to Moscow.

In summary, the France of 1940 was a nation which had been in decline relative to other countries since the 1850s, a fact recognized by some French officials. In 1921, for example, the veteran French diplomat and former ambassador to the United States Jules Cambon told a colleague that “in the immediate future, the difficulty will be to slide France reasonably into the ranks of the second-rank powers to which she belongs.”

Many domestic and foreign observers, however, put their faith in what seemed to be significant measures of enduring strengths on France’s part. Many observed that France had not only managed to build the Maginot Line, the world’s most sophisticated defensive fortifications, in the middle of the Depression; it had also successfully modernized its navy. Others noted that French industry had managed to build better quality tanks than those of Germany. Yet others stressed that Paris remained one of the world’s three major financial centers. Above all, despite the rise of the extreme left and extreme right, the Third Republic had not collapsed like Spain into civil war in the 1930s. Nor had France embraced authoritarian forms of government like interwar Germany, Austria, Italy, and Poland. These political facts alone injected confidence that France’s best days were not necessarily behind it.

National decline takes time and is often imperceptible to even seasoned observers. Neiberg notes that some U.S. diplomats claimed to have understood that France was slipping in the great power stakes, though he adds that such statements were invariably made after 1945. What’s not in doubt is the seismic shock that rolled through Washington when the unthinkable occurred in 1940. It produced, Neiberg argues, a series of responses that compounded the effects of the original error, but also generated a fundamental re-orientation of America’s view of how to engage with the world that has, for better or worse, persisted.

Vichy Time

Today the word “Vichy” is a synonym for official collaboration with foreign powers that have suborned your country. Between 1940 and 1942, however, Vichy France embodied a political reality that could not be ignored. Despite some dissenting voices, President Franklin Roosevelt’s administration maintained diplomatic relations with Vichy until mid-November 1942 when the Allies invaded French North Africa. Britain was quicker to recognize, Neiberg points out, that Vichy was never likely to take France back into the war on the Allied side. By July 1940, London had embraced General Charles de Gaulle who, for all his erratic behavior, was unquestionably committed to victory over Germany.

Vichy was never popular in American public opinion. For American policymakers, however, decisions like sending financial aid and an ambassador to Vichy were necessary parts of a strategy to keep as much of France’s colonial empire (particularly French North Africa) and its navy out of German hands—at least until America had translated its overwhelming economic power into unstoppable military clout.

But there was a price to be paid for this. One was moral. America’s association with Vichy made it, Neiberg writes, “much more difficult for the United States to claim a moral high ground or to stand on the lofty principles of the Atlantic Charter.” This was especially the case after Vichy’s official embrace of anti-Semitic policies and the collaborationist stance vis-à-vis Berlin formally adopted by Marshal Pétain and Prime Minister Pierre Laval from October 1940 onwards. In political terms, Washington’s ongoing relationship with Vichy introduced awkwardness and deep tensions into America’s relationship with its British ally insofar as the latter had opted for de Gaulle. America and Britain often consequently found themselves working at cross-purposes at a time when this was hardly optimal.

Underlying Roosevelt’s approach to Vichy, Neiberg states, was his conviction that it was possible to bring Petain’s regime on-side and woo it away from its growing entanglement in Nazi Germany’s darkest designs. (Some will recall that Roosevelt also believed that he could, through sheer charm and personality, “handle” Stalin and the Soviet Union.) That went together with a deep hostility to de Gaulle, whom Roosevelt considered a closet authoritarian. Whatever one thinks of de Gaulle, Roosevelt’s attitude reflected a serious misreading of the man and his political outlook. It also led to the United States seeking non-Gaullist alternatives by flirting with dubious characters like one of Vichy’s leading politicians, Admiral François Darlan, or cultivating figures such as General Henri Giraud who, for all his personal bravery, possessed neither de Gaulle’s political skills nor his prestige among the Resistance in mainland France. De Gaulle, it is worth adding, never forgot how shabbily he had been treated by Roosevelt. Those memories likely contributed to the intensity of the clashes in the 1960s between de Gaulle, as president of the Fifth Republic, and the Johnson Administration on topics like international monetary policy, the Vietnam War, and recognition of mainland China.

Insecurity Never Again

One factor driving U.S. foreign policy after June 1940 was the deep insecurity that America experienced after France’s defeat. “The basic assumptions,” Neiberg states, “that underlay the sense of safety Americans felt from the crises of Europe vanished overnight.” On several occasions Neiberg underscores the panic which swept the United States once it was realized that if the Axis secured use of France’s navy or bases throughout the French empire which, after all, spanned the globe, the American homeland could be directly threatened.

At the time, America’s military was ill-equipped to respond to these rapidly altered conditions. Yet this situation also led, Neiberg comments, to “an unprecedented opening of the American treasury for spending on defense, new laws to conscript men into military service in peacetime, paranoia over potential fifth columnists, secret wiretaps, new alliances, and much more.” America’s first peacetime draft began in September 1940, when Roosevelt signed the Selective Training and Service Act, 15 months before Japan’s attack on Pearl Harbor. Would such measures have been implemented if France had not been crushed in 1940? Though we will never know for certain, the answer is surely “probably not.”

The most lasting impact upon the United States of the perilous circumstances in which it found itself in 1940, Neiberg argues, was that America would never again “trust so much of its own safety to the military power of a third party.” This produced a radical recasting of American foreign and defense policy. After 1945, this was manifested in large peacetime defense spending, the maintenance of a large standing military, and the establishment of American military presences across the globe. This, Neiberg points out, is “quite unusual in American history.” It has also lasted until today.

Obviously, that is not the whole story. America’s postwar military commitments to organizations like NATO and ANZUS were partly driven by the realization that no one else had the strength and, in some countries’ cases, the will to contain Communist aggression. Neiberg does not deny this. His point is more of a long-term character: that an event which had been long in the making—i.e., France’s final disappearance from the ranks of the great powers in 1940—had major repercussions for international relations as well as profound domestic, economic, and foreign policy implications for the nation that has often described France as its oldest ally.

Ironically, America now finds itself in a reverse position insofar as many of its allies have relied, and continue to depend, on America to protect them, whether from Russia or, now it seems, China. The ongoing failure of some American allies to meet their defense spending commitments—something which Republican and Democratic administrations have complained about for thirty years—suggests that they have to some extent outsourced their defense to the United States: much as America engaged in its own outsourcing to the French army between 1920 and 1940. And if it is the case that America’s willingness to play this post-1945 role is presently fading, nations across the world ranging from Australia in the South Pacific to France itself in Europe may find themselves facing situations akin to that of America in June 1940. Foreign policy transformations, it turns out, have a way of repeating themselves, albeit in unexpected ways and places.