When Presidents Fight the Last War: The Oval Office, Sunk Costs, and Wartime Decision-making Since Vietnam

When Presidents Fight the Last War: The Oval Office, Sunk Costs, and Wartime Decision-making Since Vietnam by Bryan N. Groves. University Press of Kentucky, 2025, 256 pp.

In When Presidents Fight the Last War: The Oval Office, Sunk Costs, and Wartime Decision-making Since Vietnam Bryan N. Groves seeks to answer a complex mystery of US foreign and military policy: “how US presidents have decided what to do when major military interventions in Vietnam’s shadow are not going well” (8). It should be noted that he also addresses this question in the shadow of the post-September 11 realities, despite the title of the book.

Groves, a Special Forces Colonel, a member of the Secretary of Defense’s team that wrote the 2025 National Defense Strategy, and a prolific scholar who earned a PhD from Duke in national security policy has a unique perspective in the commander-in-chief’s wartime decision making.

Through rich explorations of five post-Vietnam conflicts, Groves compares presidential decision-making using five examples: Ronald Reagan in Lebanon in the 1980s; George H.W. Bush during the Gulf War; Bill Clinton in Somalia in the 1990s; and the post-9/11 conflicts including G.W. Bush’s decision to surge troops in Iraq and Barack Obama’s troop escalation in Afghanistan.

The first chapter serves three purposes: 1) to establish that the failures of Vietnam created echoes in US military decision-making for decades—one of the most well-established truisms in American history; 2) to explain the main argument of the book and, using traditional economic definitions, explain sunk cost traps and opportunities. However, Groves adds to his discussion by noting that presidential sunk cost issues differ from private sector sunk cost issues—the decisions are “less predictable” and “[t]he stakes are higher” (11); and 3) Groves explains why he selected these five case studies.

The second chapter makes a compelling argument that “historical ‘learning’” provides a heuristic to help presidents make complex decisions, and that Vietnam’s specter “held our historical memory hostage” until September 11 (18-19). Importantly, the chapter notes that decisionmakers often do not use the lessons of history well.

The second chapter also offers a blueprint for each of the five case studies in the following chapters. Each case study chapter is organized around a discussion of the same four questions:

1. Why was this a sunk cost trap that required a major policy pivot?
2. What were the president’s options, and what strategy did he implement?
3. What role did historical lessons and fear play in decision-making?
4. Did internal administration rationale differ from the public justifications? (25).

The following chapters (3-6) get into the individual examples and answer the questions, offering commentary on the lessons of each presidential pivotal decision. Each chapter is well done and offers the reader the background necessary to understand the event, the decision, and the role in history. I found the discussion over the consistency of internal and external justification to be especially interesting, as there was a consistent disconnect between the outcomes and the rationales behind those decisions. Groves makes a strong argument that after the September 11 terrorist attacks, rather than living in the shadow of the failures of Vietnam, Presidents Bush and Obama recalibrated decision-making based on the new imperative to counter global terrorism. Collectively, these sections offer perspective on the need to address different audiences when justifying any decision that may be fraught with peril.

While structured the same, these chapters differ primarily in the history of the individual events and the breadth of the policy options that advisers offered. As such, Groves makes a strong argument in each of these chapters; they are well conceived, well researched, and well defended.

Following four chapters on “sunk cost,” chapter 7 then pivots to a unique case study: President George H.W. Bush’s declination to move troops into Iraq to remove Saddam Hussein. What makes this situation unique is that rather than there being a sunk cost trap, the war effort progressed much faster than anticipated, offering the president a “sunk cost opportunity” to expand the war and depose or kill Saddam (140).  Despite the opportunity, Bush’s lesson from Vietnam was to seek “a clear victory and a clean exit,” so he did not press the evident advantage (134). The irony, then, is that “the painful lessons learned by U.S. policy makers from [Vietnam] might have saved Saddam himself from capture” (145, quoting James A. Baker).

In many ways, chapter 8 is perhaps the most important chapter in the entire book. After firmly establishing the validity of his rubric, offering excellent case studies, and providing a great deal of evidence about the impact of previous war (Vietnam) or forcibly restructured defense realities (the imperative response of 9/11), Groves turns to lessons for future presidents. While the preceding chapters establish the framework, the wisdom of this chapter makes it a tour de force. The advice is that presidents must remain engaged in conflict decisions, regularly review assumptions and reevaluate progress, make sure that ways, means, and ends are aligned, be adaptive faster than the adversary, and send clear prioritized signals.

While an excellent book, I have a few minor criticisms. I understand the lessons of Vietnam, as described in the book, but it is not clear why these lessons became conventional wisdom. What were the competing lessons of the war that were lost by administrations and their staffs? Groves notes that “[m]isunderstanding history affects presidents and their advisers’ ability to use past lessons well (20)”. One would think, then, that selecting which historical lesson to utilize might do the same.

Another criticism stems from Groves comments regarding Grenada. This is important because President Reagan, who is seemingly steeped in the lessons of Vietnam, famously declared a few weeks before the Marine barracks were attacked that Grenada “end[ed] the Vietnam syndrome that had broken the will of the American people.”¹ Was the end not complete? Was Reagan wrong from the beginning? Did he not internalize his own lesson?

Finally, Groves argues that “fear drives presidents’ sunk cost dilemma decisions during conflicts,” and offers examinations of the quality, type, and breadth of guidance that advisers offered (17). What is less clear is how post-Vietnam and September 11 fear, or other motivations, influenced that advice, not merely the resulting decisions.

In conclusion, Groves offers an excellent examination of presidents’ decisions during ongoing conflicts. He offers a convincing narrative about the outsized influence the Vietnam War and the 9/11 terrorist attacks had on presidential decision-making. The lessons he offers to policymakers should be required reading for graduate government and policy students and in professional military education. Indeed, on the penultimate page, Groves notes perhaps the major takeaway from the book: “[p]residents and their advisers would be wise to ready themselves [for a sunk cost decision in future conflict]. The preferred learning method is from others’ mistakes and before a crisis begins” (184).

Dr. Tobias T. Gibson