This week marks fifty years since the United States withdrew its last troops from Vietnam. It was the end of America’s bloodiest war, as measured by American casualties, since World War II. The departure of the last troop-bearing plane culminated in a sixty-day withdrawal period as specified by a peace agreement that Henry Kissinger and Le Duc Tho had negotiated and was signed in Paris in January 1973.

I was on that last plane. As an Army lieutenant in a unit that processed personnel coming in or out of Vietnam, I had to manage the departure of other GIs who were still in Vietnam before my colleagues and I could pack our own bags and head for home. That experience sparked a lasting interest in the ending of wars that became the subject of a doctoral dissertation and book and the focus of much thinking about subsequent conflicts.

The peace agreement of 1973, notwithstanding what many contended were its flaws, was the right U.S. course of action at the time. Not to reach that agreement or something very much like it would have meant the perpetuation of costly U.S. involvement in a conflict that inevitably would have lost to a movement—the Viet Minh, which became the North Vietnamese regime—that embodied Vietnamese nationalism and had the wind of decolonization at its back.

Some war-ending agreements are inevitably as unpopular as they are necessary. Domestic criticism of the Vietnam policies of Kissinger and President Richard Nixon came primarily from those who contended that the United States should have pulled out of that war sooner. But criticism also came from those who believed—a belief that has lingered in a few small circles for decades—that the United States still could have achieved a successful outcome of the Vietnam War if it had stuck it out.

This picture parallels criticisms of the Biden administration’s policies toward the war in Ukraine, with some arguing that the United States should pull back from its support for the Ukrainian war effort and others calling for an increase in that assistance. Such disagreements are partly about how the war ought to be fought, but they also are disagreements over how the war can and should end, because the arguments carry corollaries about what conditions on the battlefield will or will not produce conditions at the negotiating table conducive to reaching a peace agreement.

Compromise agreements are the rule, and outright victory or defeat the exception, in wars that have mattered to the United States since the end of World War II. Both sides typically leave the negotiating table dissatisfied about some things, and that was true of the 1973 Paris agreement. The dissatisfactions on the U.S. side were matched by Hanoi’s frustration in having to postpone yet again—as the Viet Minh had done when negotiating with the French in 1954—their objective of ruling over a unified Vietnam. Perhaps it was a mark of this frustration that the airbase where I was stationed was rocketed by Communist forces after the agreement was signed and ninety minutes before the cease-fire went into effect. It probably would have seemed like a waste to have carried those munitions all the way down the Ho Chi Minh Trail without getting in one last blow at the Americans.

For some peace agreements to be reached at all, they may have to leave much to chance. No one could have predicted with precision how events would play out in a contest between North and South Vietnam with American forces gone. Nixon and Kissinger expected that South Vietnam would be unable to stand indefinitely but would stand long enough for Americans to largely forget about Vietnam and move on to other issues. This was the concept of a “decent interval,” which deserves criticism insofar as the strategy was motivated by domestic political considerations. Nonetheless, the leaving of much of the immediate future of South Vietnam to chance probably was essential in closing the negotiating gap between Washington and Hanoi and reaching any agreement at all.

Mistaken wars are especially prone to messiness when they finally end, or when the United States pulls out of them. The very mistakenness usually involves the failure of a client regime to become strong enough and legitimate enough to stand on its own. Thus, the collapse of that regime is part of the ugly denouement. In Vietnam, that collapse came two years later, amid images of rooftop helicopter rescues in Saigon. In Afghanistan, it came with the collapse of Ashraf Ghani’s government in August 2021, amid images of Afghans clinging to transport aircraft at Kabul airport. The very swiftness of the latter collapse underscored the futility of the previous two decades of attempted nation-building in Afghanistan through military force.

Relationships between Washington and client regimes have constituted an important dimension of ending as well as fighting wars. Nixon had exploited that dimension during the 1968 presidential election campaign when he secretly used emissaries to urge South Vietnamese president Nguyen Van Thieu to balk at a Johnson administration peace initiative that, if successful, might have brought victory to Democratic candidate Hubert Humphrey. Having learned the power of such obstreperousness, Thieu later applied it to Nixon himself as Kissinger and Tho were nearing the end of their negotiation. One result was the devastating bombing campaign against North Vietnam in December 1972 known as the Christmas bombing—the largest aerial attack by heavy bombers since World War II—which was aimed as much at pressuring Thieu not to block an agreement as it was at pressuring Hanoi.

Today’s policy questions regarding the war in Ukraine involve correspondingly delicate and difficult questions about the relationship between Washington and Kyiv and how their interests diverge. There are major differences, of course, between that war and the one in Vietnam, including not only that the United States has not directly involved its own troops but also that Ukraine is led by a legitimate government with much popular support and has been the victim of naked international aggression, rather than the legacy of a partial decolonization. But the ending of this war is again likely to involve the persuasion of a Ukrainian ally as much as the pressure of a Russian adversary.

Anti-Vietnam War protests within the United States had been going on at high volume for several years by the time the 1973 agreement was signed. They exhibited several recurring unhelpful characteristics of many such protests, including self-righteousness, a concern more for volume and emotion than for practical effects on policy, and an apparent lack of appreciation for what it takes to wind down a war. An action such as leaking of the Pentagon Papers was treated as heroic even though the leaking did little or nothing to hasten the drawdown of U.S. troops, which already was well under way at the time of the leakage.

U.S. troop strength in Vietnam peaked at approximately 540,000 around the time that Nixon assumed the presidency. Bringing home an army that large is an enormous undertaking, in terms not just of basic logistics but also, amid an ongoing war, such things as force security and continuing a rotation of personnel that will maintain a balanced force structure in which essential support functions continue. One reflection of this is that much of my work during my year in Vietnam—even though the overall drawdown continued apace—involved processing Army personnel into Vietnam as well as out of it. Many GIs saw me both coming and—with their tours of duty cut short by the drawdown—going.

I like to think that the work of my colleagues and me during that time did more—in a very direct and quantifiable way—to get U.S. troops out of Vietnam than anything accomplished by someone with a bullhorn or a placard on an American street. The work was certainly not heroic but necessary. Along with the many mundane logistical tasks was the need to deal humanely with the disturbingly high number of troops who, by that stage in the war, had become heroin users.

The messiness continued until the end. Withdrawal of the 25,000 U.S. troops still in Vietnam when the Paris agreement was signed was supposed to be coordinated with the repatriation of U.S. prisoners of war held in North Vietnam. The coordination worked satisfactorily until the final two weeks, when disagreements over the movement of the prisoners required us to freeze our flight operations. Once that snafu was resolved, we had just three days to move out the last several thousand troops, while at the same time winding up our own unit’s affairs. I got almost no sleep during that finale, before being able to step into a C-141 and sleep most of the way across the Pacific.

Once in California, I participated in a brief ceremony at which my unit—the 90th Replacement Battalion—was formally deactivated and its colors furled. A reporter at the ceremony asked for my thoughts. I expressed hope that the unit—which had first been stood up in the European theater in World War II—would never need to be reactivated for another foreign war.