“The soul of [an] army can’t be breathed into the army by a foreign military power or a foreign military force on the ground.” Any inquiry into why the American enterprise in Afghanistan ended in abject failure should begin with this cogent observation by retired Lt. Gen. Karl Eikenberry, who commanded all US forces in Afghanistan and subsequently served as US ambassador in Kabul. “Only the Afghans,” Eikenberry emphasized “can give their army a soul and its identity.”

Most Americans today are not accustomed to thinking of armies as soulful institutions. A citizenry no longer accustomed to military service tends to view armies as bureaucratic, hierarchical, and heartless—a massive corporate enterprise designed to kill and destroy. While reflexively approving large appropriations to sustain the armed services, Americans have by-and-large lost any appreciation for what makes them tick. We underwrite, but do not necessarily understand.

So while Americans today may “support the troops,” they possess little understanding of what mix of qualities imbues an army with fighting spirit. For ordinary citizens understandably preoccupied with the pressing challenges of everyday life, that subject no longer possesses any particular importance.

Yet for an embryonic political movement, the soul of the army may well embody the soul of the nation itself. The two are intimately connected. Certainly this describes the role played by the Continental Army during the American Revolution.

The stirring saga of George Washington’s beleaguered troops crossing the Delaware to surprise the Hessians at Trenton, or wintering over at Valley Forge, may no longer set American hearts aflutter the way it once did. But the very survival of the American Republic depended on the survival of Washington’s Continentals. Merely by staying in the field—by refusing to submit despite serial defeats at the hands of the Redcoats—they kept alive the cause of Independence.

Whatever the Continentals may have lacked in terms of numbers and equipment, Washington’s troops had heart and his army had a soul.

Notwithstanding welcome help from abroad from the likes of Lafayette, Kosciusko, and Von Steuben, the soul of the young Republic’s fighting forces was homegrown. Even the arrival of very substantial French forces in 1779 did not create—but merely supplemented—the spirit that animated the Continentals.

To say that following the overthrow of the Taliban in the autumn of 2001, Afghanistan never found its Washington is something of an understatement. More to the point, a costly effort undertaken by the United States and its allies to build effective Afghan security forces produced indifferent results at best.

The United States provided Afghan forces with mountains of arms and equipment—much of it now in the hands of the Taliban. And our efforts doubtless imparted to our would-be protégés at least a modicum of fieldcraft and tactical skills. That ordinary Afghan soldiers thereby learned how to salute, march, fire a rifle, and render first aid is not the issue. That they lacked the necessary motivation to defend their country in its moment of maximum peril is.

The events of the past several weeks make it unmistakably clear that efforts by the US military and its coalition partners to nurture a soul in the ranks of the Afghan security forces came nowhere close to succeeding.

In contrast, however painful it may be to admit, Taliban fighters have demonstrated plenty of soul. Their commitment to the purposes for which they have fought for the last two decades—to expel foreign occupiers and impose their version of Islamic values—was unambiguous and unrelenting. As a consequence, despite their inferiority in equipment and (probably) in numbers, the departure of US forces found the Taliban prevailing with remarkable ease.

There is lesson here that the United States needs to learn and probably should have learned decades ago. Creating out of whole cloth an army comprised of non-Americans that will advance US policy objectives is a daunting proposition.

That is, after all, what the Afghanistan War of 2001–21 was all about. Once the Taliban had been toppled (but neither defeated nor destroyed) in the autumn of 2001, the United States embarked upon a nation-building exercise centered on creating a new Afghanistan founded on values cherished by most Americans—women’s rights, for example—but not necessarily by most Afghans.

Policy-makers in Washington never deployed a sufficient number of American soldiers to accomplish this ambitious purpose. Indeed, we may question whether a sufficient number existed.

The decision by exasperated US civilian and military officials, taken without fanfare, to turn the entire task over to Afghan troops was probably inevitable. If General Eikenberry is correct—and I suspect he is—so too was the final outcome.