“In the mid- to late 1980s I served with a unit at the Korean Demilitarized Zone, and with a paratrooper unit in Italy, and in terms of manpower and training, the all-volunteer force was light years ahead of where it had been a decade earlier,” he says. “In fact, it was becoming increasingly clear that by the metrics of discipline, morale, and reliability, the all-volunteer force was unmatched in its capability.”

That force was shaped by social engineering that increasingly distinguished it from the population at large. Because military leaders had discovered in the 1970s that units with a high percentage of minorities and an overwhelmingly white officer cadre suffered racial tensions and a lack of cohesion, they introduced measures such as remedial education and training to help increase minority representation in the officer corps. To combat rampant drug abuse, the Pentagon introduced a zero-tolerance policy for drugs and drunken driving, including random urine tests. In a more career-oriented, all-volunteer military, the number of enlisted personnel who were married had also nearly doubled, creating a more mature force and signaling an end to a military centered on barracks life. Women represented roughly 14.5 percent of the active-duty force, the highest number in U.S. history.

By 1990, with the Cold War ending and U.S. military forces massing in the Persian Gulf on the eve of Operation Desert Storm, the all-volunteer force had largely become what its creators had envisioned—a truly professional army, with a tremendous degree of competence and expertise in the increasingly high-tech weaponry of modern war. As the country was about to discover in the blanket media coverage of the first major military campaign since Vietnam, however, it was also a force that increasingly stood apart from the civilian population.

IN 1990, Lt. Col. Eikenberry, a battalion commander in the 10th Mountain Division, again had a serious morale problem on his hands. In contrast to his early days as an officer trying to quell outright rebellion in the ranks, the current headache was that the 10th Mountain had not been deployed for Operation Desert Storm, and those under his command were nearly despondent about not participating in what would prove to be one of the most lopsided military victories in the country’s history.

Eikenberry’s response was to send 10th Mountain units to the Army’s high-tech, force-on-force training centers, where they substituted for units that had deployed unexpectedly to the Persian Gulf War. They responded enthusiastically, and were thus trained to a fine edge when called on to deploy to Somalia a year later. The experience drove home two important points about the military circa the 1990s: that it was one of the best forces the United States had ever fielded, and that, from a political perspective, it was tailor-made for the coming cycle of near-constant deployments.

With President Clinton wielding a finely wrought, all-volunteer hammer, the 1990s revealed just how many international crises would begin to look like nails. In the run-up to 1991’s Operation Desert Storm, Joint Chiefs of Staff Chairman Colin Powell issued the “Powell Doctrine” to try to limit the use of military force. He argued that the U.S. should commit forces only as a last resort and when there was a vital national security interest at stake—and even then only with a clearly attainable objective, a plausible exit strategy, and broad support at home and in the international community.

Confronted with those constraints, then-Secretary of State Madeleine Albright famously asked Powell during a debate over a potential military intervention in the Balkans: “What’s the point of having this superb military you’re always talking about if we can’t use it?” Though Powell confessed in his memoir to almost having “an aneurysm” over the comment, Albright would eventually win the argument, and in the first decade of the post-Cold War era, the U.S. military was dispatched to Haiti, Somalia, Colombia, Bosnia, and Kosovo without so much as a congressional authorization, let alone a declaration of war. Partly as a result of the relative ease of sending an all-volunteer military to global hot spots in an era of U.S. “hyper-power”—and of the competence and confidence the force routinely displayed once deployed—the balance in war powers carefully enumerated in the Constitution began to shift. Although exclusively empowered to raise armies and declare wars, Congress increasingly ceded its authorities to the commander in chief, who alone held the reins of America’s volunteer legions.

IN EARLY 2003, Maj. Gen. Eikenberry was stationed at Bagram Air Base, Afghanistan, leading a training-and-advisory command charged with creating a functioning Afghan Security Force. Being able to transfer security responsibilities to the Afghans would essentially have been a ticket home for U.S. forces, but evidence was growing that Taliban insurgents were regrouping in some rural areas and across the Pakistan border. Eikenberry says he stressed the point during a video-teleconference with Gen. Tommy Franks, the head of Central Command, asking Franks to deploy another active-duty combat brigade to replace one scheduled to rotate home from Afghanistan.

From his headquarters in Tampa, Florida, Franks was having none of it. “No, I’m going to send you a National Guard brigade,” Eikenberry says Franks insisted. Both men understood that the Guard brigade represented significantly less capability than its active-duty counterpart. Eikenberry argued his case that securing their gains in Afghanistan against the Taliban and al-Qaida remained the “main effort” of the “global war on terrorism,” but his boss would not budge.

At that moment, Eikenberry says, he understood that back-channel rumors that the United States was poised to invade Iraq were probably true. The decision to open up a second major military front seemed rash to him, he recalls, but that was far above Eikenberry’s rank or pay grade. More troubling to him at the time was the realization that the all-volunteer force was insufficient to the task at hand—and, little more than a year after the 9/11 attacks, was already heavily reliant on the Reserves and the National Guard.

“The lessons we learned from all of the deployments in the 1990s were useful, but they tended to be relatively short-term deployments that did not overly strain a much larger force,” says Eikenberry. By the turn of the millennium, the post-Cold War drawdown had reduced the size of the military by roughly a third. “So that moment in Afghanistan in 2003, when I realized we were also going to invade Iraq, is when the light went off that the all-volunteer force was too small for the missions it was being given,” he says.

The military’s heavy dependence on the National Guard and Reserves had actually been built into the “Total Force” in 1973 by Army Chief of Staff Creighton Abrams, who at the time was furious at political leaders for never having mobilized the National Guard during the long years of Vietnam—thus, in his opinion, failing to rally the nation behind that war effort. Concerned that an all-volunteer army would prove even more susceptible to being sent off to foreign lands without widespread public support—essentially treated as a Foreign Legion in the service of the commander in chief—Abrams placed critical support functions required for any large deployment almost exclusively within the National Guard and Reserves, front-loading a future president’s weighty political decision to call them to active duty. And for a time, it worked.

The manpower contribution of the Guard and Reserves would peak in 2005, when they represented roughly 40 percent of the U.S. military forces deployed to Afghanistan and Iraq. Such a heavy dependence on part-time warriors was not sustainable, however—nor politically expedient. Defense Secretary Donald Rumsfeld therefore shifted a number of support functions from the Reserves back to the shoulders of an active-duty force that was already stretched thin, even as he grudgingly ceded to repeated military requests to grow that force by roughly 100,000 troops in the coming years. By the time of the Iraq “surge” of 2007, the Reserves’ manpower contribution had fallen to roughly 20 percent, a perilously narrow bridge between the active-duty military and citizen soldiers.

BY 2007, Lt. Gen. Eikenberry had already been back in Afghanistan for more than a year, in command of all U.S.-led coalition forces. The growing strains on the military were increasingly evident by that time, he says, as were the costs of not having enough troops available to effectively fight on two fronts. With the Iraq surge in full swing, the military was again forced to lower its standards, accepting more recruits who were high school dropouts, had felony convictions, or scored in the lower mental categories.

When Eikenberry requested an active-duty brigade to secure a particularly dangerous region of Afghanistan where the Taliban was making a comeback, he says, he was informed that none existed. The decision was made instead to extend the deployment of a brigade of soldiers who had already been in-country for 12 months, lengthening their tour to 15 months. This was a wrenching and increasingly common disruption that played havoc with the lives of troops and families who had been nervously counting down days on the calendar, many of them already enduring a second or third combat tour. Back home, the Pentagon was also issuing “stop loss” notices to service members whose enlistments were already fulfilled, blocking them from leaving military service because their units were scheduled to deploy and couldn’t spare them.

Between 2006 and 2007, the Iraq War teetered on a razor’s edge, even as all indicators trended negative in Afghanistan, with the Taliban insurgency and its Qaida allies regaining strength by the day. And yet, not once did the Bush administration or Congress seriously raise the possibility of a return to conscription or even a general mobilization of the Reserves.

“In 2007, as the U.S. commander of the coalition in Afghanistan, it became very clear to me that we simply didn’t have enough forces to accomplish our mission,” says Eikenberry, adding that Adm. Mike Mullen, then-chairman of the Joint Chiefs, summarized it best with the line: “In Afghanistan, we do what we can; in Iraq, we do what we must.”

One lawmaker did champion the idea of returning to a draft. In an appearance on Fox News in 2006, Democratic Rep. Charles Rangel, a New York liberal and a decorated veteran of the Korean War, asked, “Why is a kid who is going to Harvard or Yale or has alternatives not included in the sacrifice for our country? Why will you recruit people who have less options?” Conscription, he argued, would also discourage lawmakers from backing further wars for which adequate forces did not exist. “Every time someone says ‘more troops,’ or the military option is on the table in Iran, and the military option is on the table in North Korea,” Rangel said, “they’re saying that somebody’s kids are going to be placed in harm’s way, but not mine.” The Universal National Service Act that Rangel had sponsored in 2004, dubbed the “Reinstate the Draft” bill, would have committed all American 18- to 26-year-olds to two years of service. The bill was buried in the House of Representatives, 402-2.

As a military commander in a combat theater, Eikenberry says, he had neither the time nor the inclination to reflect on the long-term implications of this new normal in the American model of war, but the seed of an idea was planted within him in those desperate days, and it would blossom darkly in the years to come. By the time he returned as ambassador to Afghanistan in 2009, it had manifested itself as a deep discomfort with the path the nation had turned down, way back in 1973, when both he and the all-volunteer force were young.

“When you’re in uniform and fighting in the belly of the beast, you don’t have time for much introspection, so I just internalized my growing sense of unease,” Eikenberry says. Returning to Afghanistan in 2009 as a civilian ambassador, however, gave him a fresh perspective on the nature of the all-volunteer covenant. “Even though my office in the Embassy in Kabul was only half a mile away from my former military headquarters, I was able to see the issue from an entirely different angle. And like a lot of former military commanders and senior civilians after they have had time to reflect on their experiences in Iraq and Afghanistan, I was profoundly troubled by this new model the nation had adopted for fighting its wars, even large wars of extended duration.”

IN 2009, classified cables in which Ambassador Eikenberry argued that mercurial Afghan President Hamid Karzai was an unreliable partner were leaked to the press, revealing the fraught relationship between the two men. But Eikenberry couldn’t say he didn’t understand why he was called into Karzai’s office on a regular basis to hear complaints that Afghanistan had been overrun by a massive secret army that was truly accountable neither to the Afghans nor to the U.S. and NATO high command.

The United States’ unprecedented reliance on private contractors to prosecute the wars in Iraq and Afghanistan was directly linked to the decision not to fully mobilize the Reserves or return to the draft. The modern American model of warfare requires a huge support apparatus for force protection, for the logistics of moving massive amounts of war matériel, and for mundane aspects of troop support such as base maintenance and food preparation. With far too few troops for those functions, the Pentagon quietly shifted the burden to private contractors, and Eikenberry says this caused him no end of grief.

When he lectured Karzai and other Afghan leaders about the need to establish the rule of law and an independent judiciary in their country, for instance, they often threw back in his face the fact that the United States had compromised Afghan sovereignty by essentially inviting an unaccountable hoard into their midst. The U.S. military lacked authority to apply military justice to civilian contractors, so frequent instances of misbehavior usually led to the contractors being whisked out of the country by their employers, only to be replaced by others, many of them armed and dispensing lethal force as security personnel.

Of equal concern to Eikenberry was that the unprecedented use of private contractors allowed U.S. political and military leaders to obscure the actual costs of the wars in Afghanistan and Iraq from the public.

In 2009, the new Obama administration was in a tug-of-war with military leaders over the number of troops needed for a surge in Afghanistan to turn back a resurgent Taliban. Gen. Stanley McChrystal, the top general in Afghanistan at the time, made it known that he preferred the maximum option of 40,000 additional troops, which would bring the total U.S. troop presence to around 100,000. The Obama administration eventually settled on 30,000, with NATO allies picking up some of the slack—a difficult concession for a president elected to end the unpopular post-9/11 wars.

Eikenberry, who opposed the surge, says he agreed with some in the White House who believed that President Obama was being “gamed” by the military, offered a series of “options” that carried such “high risk” warning labels that practically the only viable choice was the military’s preferred alternative. That was another way the all-volunteer military had affected civil-military relations, in Eikenberry’s view: by making the military a privileged player in highly charged political decisions about the use of force—a player with specialized knowledge and expertise the political class no longer possessed. He heard it in the response of candidates for president when they were asked how they would address this or that international crisis: “I would listen to the advice of my generals.” As if some of the best wartime presidents in American history, including Abraham Lincoln and Franklin Roosevelt, had not constantly prodded and occasionally overridden their generals.

And in the debate over the troop surge, almost no mention was made of the fact that, between 2007 and 2011, private contractors outnumbered deployed military personnel in both Iraq and Afghanistan, peaking at more than 200,000. That compared with just 4,000 private contractors hired to support more than half a million U.S. troops deployed for Operation Desert Storm in 1991. Because contractors are expensive, that historically unprecedented reliance upon them helped make the post-9/11 wars in Iraq and Afghanistan the second-most-costly armed intervention in U.S. history, behind only World War II. Today, it requires more than $2 million to keep a single U.S. service member in Afghanistan for a one-year deployment.

In earlier times, such astronomical costs might have sparked a public backlash against the wars. In fact, the 1970 Gates Commission put its faith in just such an outcry to place brakes on the use of the all-volunteer force. “If tax increases are needed or military spending claims priority over other public spending, a broad public debate is likely,” the Gates commissioners concluded. “Recent history suggests that increased taxes generate far more public discussion than increased draft calls.”

Because the public was never asked to pay so much as a war tax for Iraq and Afghanistan, however, and because both were put on the credit card of a nation inured to deficit spending, the anticipated public outcry was muted. That final step in the untethering of the all-volunteer force from a direct cause-and-effect calculation on the part of the 99 percent of the public that did not serve, Eikenberry came to believe, helped explain why the wars in Iraq and Afghanistan were not only among the costliest, but were also the longest in American history.

“Because Thomas Gates was an Eisenhower Republican and fiscal conservative, and the commission was working at a time when the notion of balanced budgets dominated political debate, they wrongly assumed that the costs of military deployments would serve as a brake on future presidents,” says Eikenberry. “Not only did the commission vastly understate the costs of an all-volunteer force by not including the price of health care or retirement benefits in their calculations, however, but they also never foresaw that the American taxpayer would get so comfortable with deficit spending and borrowing from the future.”

PERHAPS NO OTHER attribute of the all-volunteer force came to worry Eikenberry more, however, than the change it produced in the nature of congressional oversight and engagement with the military. As ambassador to Afghanistan, Eikenberry hosted scores of congressional delegations, walking visiting lawmakers and their staffs through the details of a complicated campaign of nation-building in a time of war. The visits usually started with a briefing by senior U.S. military leaders in command of the International Security Assistance Force. Time and again, Eikenberry says, he watched as lawmakers sat mute before the military PowerPoint presentations, asking very few questions of the generals other than requesting a photo-op for their congressional Web pages. Yet at the Embassy, the same members of Congress would frequently grill the civilians of the State Department and the U.S. Agency for International Development, demanding that they justify in great detail budgets that amounted to a small fraction of the massive military expenditures.

Eikenberry says he would frequently call lawmakers out on the disparity in oversight. “But, Congressman, you just talked to the military and didn’t bother to ask them how efficiently they were managing their ammunition during firefights. My civilian team has been given a similarly difficult task.” After enough of those scenes, Eikenberry says he concluded that because so few lawmakers had military experience on their résumés, or constituents either fighting on the front lines or protesting back home, they didn’t feel qualified or obligated to press military leaders on their decisions.

“Frankly, I didn’t see it as a general and military commander—but as a civilian, I saw clearly that the lawmakers rarely asked the military the tough questions about how to measure success in Afghanistan that they asked civilians,” Eikenberry says. “They showed a kind of deference to the military, almost as if asking military commanders tough questions would seem unpatriotic or lacking in concern for the troops. So they gave the military a pass.”

That epiphany was driven home for Eikenberry during a string of “green on blue” attacks conducted by disgruntled Afghan troops and police, who turned their guns on their U.S. and coalition counterparts. Over an 18-month period between 2011 and 2012, 46 coalition soldiers were killed in these demoralizing instances of fratricide, and Eikenberry awaited the angry call for him to return to Washington to explain the trend to an outraged public and Congress. The call never came. Instead, Congress held a single hour-and-a-half hearing on the issue, which generated almost no media attention.

What might lawmakers have learned in Kabul if they had sent the generals and other senior officers out of the room and sat down with the troops who were bearing the brunt of the fighting? They might have learned that the rank and file were suffering from unprecedented levels of post-traumatic stress, a reaction to the industrial-level violence of modern warfare made much more acute by the back-to-back-to-back combat deployments.

The lawmakers might have learned that many of the troops were among the more than 320,000 service members and veterans of Iraq and Afghanistan that a Rand survey estimated were suffering from concussions or traumatic brain injuries as a result of improvised explosive devices, the enemy’s signature weapons in these wars. Or that they were friends with some of the more than 1,400 U.S. soldiers who had, according to the Journal of Military and Veterans’ Health, lost limbs to those weapons. They might have heard stories that explained why, in some months of the war, more service members were dying of suicide than from hostile fire, and why the troops were suffering from unprecedented levels of depression, drug and alcohol abuse, failed marriages, and emotional distress. They probably could have put some faces to the Congressional Budget Office estimate that the medical costs associated with today’s veterans could climb to between $40 billion and $55 billion over the next decade, another unanticipated consequence of a new model of war.

“If we had been in the 10th year of war with a draft force, and those soldiers and Marines were there because of their obligation as citizens rather than because they raised their hand to volunteer, then I believe visiting members of Congress would have sat down with troops from their districts and asked about their experiences and troubles,” Eikenberry says. “Otherwise, lawmakers would get a lot of flak from their constituents when they got home. And, unfortunately, those conversations just didn’t happen.”

THE U.S. MILITARY has a tradition of sending officers to schools after operational deployments, the better to take stock of their experiences and consider “lessons learned.” So when he stepped down from his post as ambassador to Afghanistan in 2011, Eikenberry repaired to Stanford University to reflect. There, he teamed up with military and sociology experts including Pulitzer Prize-winning historian David Kennedy to write a 2013 anthology titled The Modern American Military. In it, Eikenberry, Kennedy, and the others set about trying to answer a nagging question frequently asked by service members suffering from a sense of alienation as they cope with multiple combat deployments and the accumulating burdens of a decade of conflict: “How can it be that the U.S. military is at war, but the nation is not?”

Eikenberry says he felt the alienation of that arrangement acutely, as both an ambassador and a general, returning home from multiple deployments to Afghanistan to find most Americans and their leaders remarkably uninformed about and unencumbered by the war being fought in their name. Polls showed that the long wars in Afghanistan and Iraq were deeply unpopular, but where were the college-campus protests demanding their end? Where were the congressional hearings held to channel that rage, the modern equivalent of the Fulbright hearings of the late 1960s and early 1970s that crystallized opposition to the Vietnam War?

Eikenberry and the other authors sketched out the seismic shifts that collectively ended a two-century-old American tradition of the “citizen soldier”: the post-World War II decisions to maintain a large standing military force in peacetime to pacify Germany and Japan, and to sustain a globe-spanning architecture of military alliances and bases to contain the Soviet Union and deter World War III; the abolition of the draft; and the post-Cold War era of nearly constant deployments as the “indispensable nation” attempted to police an increasingly fractious international order in places such as Panama, Somalia, the Balkans, Iraq, and Afghanistan.

In his article “Reassessing the All-Volunteer Force,” published in The Washington Quarterly in 2013, Eikenberry set out to explore more deeply the role that ending conscription had played in creating the disconnect he saw. “What drove me to write that article was coming back to the United States from tours in Afghanistan, both in and out of uniform, and finding that the American people were so extraordinarily uninformed about the war. They were interested, but even well-educated people I met were abysmally unaware of the reality,” Eikenberry says. “In 2009, I had seen polling that indicated a majority of the public had turned against the Afghan War, for instance, and yet we were sending an additional 50,000 troops there! In a democratic society, why had the discontent with the war not translated into congressional pressure to force the administration to make clearer what our goals were, and to educate the public on the war effort? So I felt this great discomfort that the U.S. military and those of us supporting their effort in Afghanistan were at war, but the nation wasn’t.”

Indeed, without being asked to do so much as pay a war tax, and with few direct ties to a volunteer military that for decades had evolved largely apart from the rest of society, the vast majority of Americans were relegated to the role of bystanders in their own country’s life-and-death struggles. In airports and train stations, people often politely tell those in uniform, “Thank you for your service.” Little wonder that many of those on the receiving end of that platitude interpret it as, “Thank you for making it possible for me not to serve.”

ON A BLUSTERY NOVEMBER MORNING in 2014, Karl Eikenberry, now 63, close-cropped hair going gray at the temples, stands in khakis and a sports coat before a class at Prince-ton University. With the last U.S. combat troops poised to leave Afghanistan the following month, ending the longest war in American history, the students naturally want to know what lessons he has taken away from the experience.

One thing he has learned—one thing he knows for sure—is that few if any of the students before him, the scions of American wealth and power, will ever serve in the armed forces.

The less than 1 percent of the U.S. population that Eikenberry led in wartime were the sons and daughters not of Wall Street hedge-fund managers or high-tech entrepreneurs, but of working-class cops, teachers, firefighters, and especially other soldiers. One 2007 U.S. Army survey cited in The Modern American Military found that the 304 general officers in the military had 180 children serving in uniform, making military service something of a family business. By contrast, the editor’s own research indicated that, of the 535 members of Congress, the country’s political elite, fewer than a dozen had children in uniform. Since the establishment of the all-volunteer force, military experience in Congress has also dropped precipitously, with the number of members who served in uniform falling from 398 in 1971 to only 118 in 2013.

Rather than coming from the urban power centers and Ivy League schools of the Northeast and West Coast, military volunteers hailed disproportionately from the rural South and Mountain West, which not coincidentally played host to more than their share of major military bases and installations. The ranks were filled disproportionately by African-Americans, while Hispanics and especially women were underrepresented. As a caste they also adhered to a martial ethos that, especially after a decade of war, was increasingly at odds with the norm on leafy campuses like Princeton.

Eikenberry does not advocate a return to the draft. He says he understands that there is no political constituency in the American body politic for such a dramatic reversal—and that military leaders, now accustomed to a level of competency attainable only by a force of professionals, wouldn’t embrace conscription if given the choice. As commanders in chief, presidents covet the unprecedented freedom of action that an all-volunteer force bestows, unshackling them from the necessity of requesting conscription authority from balky Congresses. For their part, members of Congress have not exercised their constitutional prerogative to declare war since World War II. They increasingly seem inclined to cede decisions on the use of military force to the executive branch, preferring to criticize and score political points from the sidelines. For the generations of Americans who have come of age in the all-volunteer era, war has become an abstraction, something best left to the professionals.

Yet Eikenberry is not alone among his former peers in his desire to somehow renegotiate the compact between citizens and soldiers, to close what many see as a dangerously widening gap in perspective and values. Chairman of the Joint Chiefs Martin Dempsey has launched a program called “Commitment to Service,” in which service members and veterans work with civilians to address common problems such as hunger, the better to form new bonds of shared experience. Last Veterans Day, McChrystal called for the establishment of Universal National Service for Americans ages 18 to 28, to counter “the current cultural expectation that service is only the duty of those in uniform.” Former Defense Secretary William Perry has proposed returning to a strengthened “Total Force” model that would require major and sustained National Guard and Reserve mobilization in the case of conflict. Other proposals have included a mandatory war tax to fund deployments, and congressional actions to require Authorizations for Use of Military Force that include sunset clauses that limit the duration of deployments and ensure a more engaged public debate. “Somehow,” Eikenberry says, “we have to find ways to reconnect the American people and their armed forces, so that there is a more direct and visceral understanding of the political, social, and economic costs of war.”

At the end of this month, the last U.S. combat troops will return from Afghanistan. They will not be greeted by ticker-tape parades or victory celebrations. Like millions before them over the past decade, they will instead come home just as they left, largely invisible to a distracted nation. For Eikenberry and other emissaries from the front lines, there remains something deeply disturbing about this new civil-military compact, which calls on a few to fight and sacrifice, and allows the vast majority to remain above the fray.

CORRECTION: An earlier version of this story misstated Karl Eikenberry rank in 1990. Lt. Col. Eikenberry was then a battalion commander in the 10th Mountain Division.