Last week marked the fiftieth anniversary of America’s culminating point in Vietnam, the Tet Offensive. In an uprising that consumed most of the country, the Vietcong and North Vietnamese Army surprised American and South Vietnamese forces by attacking during the Tet holiday, the Vietnamese New Year celebrations. Confronting American firepower in the open, the communists took devastating losses in the months of fighting that followed. However, the massive surprise attack put the lie to the Johnson Administration’s predictions of imminent victory. Though communist forces were annihilated on the battlefield, the Tet Offensive crippled American support for the war.

There has been no shortage of books and documentaries juxtaposing our tactical victory and strategic defeat at Tet. Last year Ken Burns titled the Tet episode of his Vietnam War series “Things Fall Apart.” The valor of the men who fought at Khe Sanh and the Saigon embassy is getting a belated surge of recognition. But perhaps we should mark Tet’s anniversary by looking more closely at who our soldiers were than at what they did. In doing so, we may find the beginning of the cultural, social, and economic fissures that increasingly threaten to split America in half.

America’s wars have always had those who did not answer the call, from Thomas Paine’s “sunshine patriots” to Hollywood heroes who kept themselves well clear of the real sands of Iwo Jima. Prior to Vietnam though, elites generally did their duty—or at least enough of them did to keep faith with the nation. Politicians and businessmen led regiments on both sides in the Civil War, Teddy Roosevelt charged up San Juan Hill, Wild Bill Donovan earned the Medal of Honor in the trenches. Kennedys and Roosevelts fought and died in World War II. Future journalist Arthur Hadley went from Groton to the U.S. Army in 1943. Yale could wait.

Vietnam was different. Driven by the technocratic concept of “channeling” the most intelligent Americans into critical non-military occupations, the post-1948 draft provided deferments to university students. The majority of the 15.4 million draft deferments given out during Vietnam were student deferments. This loophole was largely closed to working class Americans by only being available to full-time college students. Employed part-time students, who were invariably from humbler backgrounds, were ineligible for student deferments.

Medical exemptions offered other perverse rewards to wealth. An entire cottage industry sprang up to advise young men on how to fake injuries, insanity, ill health, and other conditions that would obviate military service. Self-mutilation was a rare equal opportunity option. Wealthier men who could afford to pay for professional documentation of an ailment (or, in extremis, get braces) had a 90 percent chance of receiving a physical or psychological medical deferment from military physicians who lacked the time and desire to challenge them.

For others with connections the reserves and National Guard offered another refuge. With all these avenues for the upper class to avoid combat service, it is small wonder that many elite U.S. universities can count their Vietnam war dead on one or two hands. Journalist James Fallows could only recall two of his 1200 Harvard classmates who served in combat in Vietnam.

Marine and future Senator Jim Webb summed it up well in his novel Fields of Fire: “Mark went to Canada. Goodrich went to Vietnam. Everybody else went to grad school.” The elimination of the graduate school deferment after Tet and the institution of the draft lottery in 1969 did substantially raise the proportion of college graduates sent to Vietnam in the last years of the war. By that point Vietnamization was in full swing and U.S. operations and troop numbers were being reduced.

The class and educational profile of the U.S. Army had practical effects in Vietnam. More important was what the elite deferments did to the social fabric of the nation. Fortunate sons (many of whose fathers had served with distinction in World War II or Korea) avoided combat while the middle class and poor went to fight in a losing war. Eighty percent of the men who went to Vietnam had no more than a high school education, at a time when nearly 50 percent of Americans between eighteen and twenty-one had some college education.

Even the officer corps was not exempt from the upper class’s turn from service. In writing The Long Gray Line, about West Point’s class of 1966, Rick Atkinson found that before World War I nearly a third of the Corps of Cadets were sons of doctors, lawyers, and other professionals. By the mid-1950’s, “links to the upper class had been almost severed. West Point increasingly attracted military brats and sons of the working class.”

Few American 19-year-olds of any social class sought to fight in an unpopular and intractable war in Southeast Asia. Had deferments been available to poor and working class men most would have taken them. They were not available though, because of conscious social policy and the moral cowardice of national leaders. So the army that fought in Vietnam, unlike that of Korea and the World Wars, was not an army that looked like the nation it served.

The predominantly working class men who fought in Vietnam returned to an America split by a culture war and a long-delayed racial reckoning. They then became working adults and approached middle age in a country that was beginning to split economically, as the stable blue collar occupations of the Baby Boomers receded and median wages stagnated. Only about four percent of men in the peak Vietnam cohort finished college after their service. Vietnam veterans were far less likely to join the managerial class than their countrymen who had not fought.

Today there is clearly little to no stigma attached to eligible men who did not serve in Vietnam. Indeed, it is treated as the statistical norm that it is. The presidency and vice presidency have repeatedly been occupied by men who “had other priorities” in the 1960’s. Avoiding Vietnam has been no bar to advancement in Washington, nor has it been an impediment to calling for other Americans to fight and die in other questionable interventions. It is one of history’s ironies that Vietnam veterans likely played an important role in electing the three recent presidents who avoided serving in Vietnam by various means.

Today, in the midst of what some still insist on calling “the Long War,” military service is entirely voluntary. Our “all volunteer” force has maintained high standards for now – Robert McNamara’s Project 100,000 would be unthinkable in 2018. But our military boasts only a few senator’s sons. Its officers are far more likely to come from Southern state schools than from the Ivy League. When the sons and daughters of our elites choose Silicon Valley or SoHo over service, we should not be surprised. We should also not be surprised when those who do serve, or at least know those who do, nurse deepening resentments against the sacrifice-free leaders who would send them off to fight dubious wars.

As documented by men of both the right and the left, the wealthiest and best educated Americans have less and less of a stake in their nation. The elites increasingly live apart (in what Charles Murray dubbed “SuperZips”), learn apart (in highly selective private schools and universities), and work apart (in the lucrative cognitive fields of the knowledge economy). Some of our top 0.1 percent go so far as to buy domestic fortresses or foreign estates as insurance in the event that their country collapses on itself. Never before have our elites had so little skin in the game.

The widening gulf between American elites and the rest of their countrymen has many causes and few apparent solutions. Economics, technology, government policy, and geography have combined to create a society that is increasingly unequal and increasingly divided. We are becoming, if not two nations, then two cultures. If Americans are searching for the moment when that chasm began to open, we should look anew at Tet and at the men who were fighting in Vietnam fifty years ago.

Gil Barndollar served as a Marine infantry officer from 2009 to 2016. His writing has appeared in the Marine Corps Gazette, the Journal of Military Operations, and the Michigan War Studies Review.