Clausewitz on Vietnam: The Summers Thesis

With all the current debate about U.S. military strategy, the nature of warfare, counterinsurgency, U.S. policy in Afghanistan, etcetera, I am surprised by the near-total lack of attention given to the work of Col. Harry G. Summers. Reading the current discussions, in the blogosphere and elsewhere, it seems as if the man and his writings have been completely forgotten. This is worse than unfortunate because Summers is just as relevant today as he was two decades ago when he was at the height of his influence.

Col. Summers was a Vietnam veteran who spent several years after the war researching the causes of the American failure. The result of this study was published in 1982 as On Strategy: A Critical Analysis of the Vietnam War, a hugely influential book that helped guide the U.S. Army’s post-Vietnam reconstruction. It has become cliche to to ascribe the American defeat to deficient counterinsurgency techniques, but this explanation is just as shallow as blaming the media or the American people for losing the will to continue the war. As Summers writes in his foreword:

One of the anomalies of the Vietnam War is that until recently most of the literature and almost all the thinking about the war ended with the Tet Offensive of 1968. As a result, the common knowledge was that America had lost a guerrilla war in Asia, a loss caused by failure to appreciate the nuances of counterinsurgency war.

But the truth was that the war continued for seven years after the Tet Offensive, and that latter phase had almost nothing to do with counterinsurgency or guerrilla war. The threat came from the North Vietnamese regular forces in the hinterlands.

The final North Vietnamese blitzkrieg in April 1975 had more to do with the fall of France in 1940 than it did with guerrilla war.

Summers analyzes the war from a Clausewitzian perspective. In Book II of On War, Clausewitz notes that the “activities characteristic of war may be split into two main categories: those that are merely preparation for war, and war proper.” Accordingly, Summers divides his study into two parts: Part I focuses on the larger policy failings surrounding America’s involvement in Vietnam, while Part II examines the actual prosecution of the war in-theater.

The central argument of Part I is that America’s greatest strategic error was the deliberate failure to mobilize the political will of the American people in support of the war. Following World War II, the dawn of the nuclear era, and the onset of the Cold War, classic military strategy went out of style as the bureaucracy sought ways to maintain an affordable defense establishment and prevent conflicts from escalating to a nuclear exchange. The result was the theories of “limited war” and the use of “systems analysis” and McNamara’s Planning, Programming and Budgeting System to guide all military and strategic decision making. War became nothing more than a diplomatic signaling exercise, and the concept of victory was abandoned entirely. According to these theories, the military and war became the sole preserve of the Executive, akin to an 18th-century European army that waged war according to the whims of the monarch. The military itself – the people who should have known better – embraced these new ideas as a means of bureaucratic survival:

Instead of being experts in the application of military force to achieve the political ends of the United States, we became neophyte political scientists and systems analysts and were outclassed by the civilian professionals who dominated national security policy under Secretary of Defense Robert S. McNamara after 1961 … Without a foundation in military art we could not compete with the rationalistic proposals of the defense analysts, and the effect was a failure in our responsibilities to present alternative strategies to our civilian leaders.

However, this state of affairs was incompatible with both the nature of warfare – which is not amenable to quantitative analysis – and the nature of the American political system, which by its very structure requires the participation of both the Congress and the people in the prosecution of a war. The Constitution stipulates that only the Congress has the power to declare war:

As The Federalist Papers clearly show, the Founding Fathers deliberately rejected the idea of an 18th century-type Army answerable only to the Executive. They wrote into the Constitution specific safeguards to ensure the people’s control of the military, and, in so doing, guarantee that the United States would not go to war without the initial support of the American people … The Constitutional requirement for a congressional declaration of war served a dual purpose. It insured public support at the outset, and through the legal sanctions against dealing with the enemy, it created impediments to public dissent. (14)

The problem is that the American public – with good reason – will become hostile to a war that is waged in their name but without their permission, which is exactly what happened. Summers cites a very relevant comment by General Fred C. Weyland:

Vietnam was a reaffirmation of the peculiar relationship between the American Army and the American people. The American Army really is a people’s Army in the sense that it belongs to the American people who take a jealous and proprietary interest in its involvement. When the Army is committed the American people are committed, when the American people lose their commitment it is futile to try to keep the Army committed. In the final analysis, the American Army is not so much an arm of the Executive Branch as it is an army of the American people. The Army, therefore, cannot be committed lightly. (11)

The doctrinal artifact of this era was counterinsurgency. In 1961, Nikita Khrushchev announced a campaign of “Wars of National Liberation,” in effect using surrogates in the Third World to attack U.S. interests while avoiding a direct confrontation with U.S. nuclear superiority. And of course, the U.S. played into Soviet hands by believing the rhetoric about a new form of warfare, unique in the annals of human history, which demanded a total reinvention of all military theory. In the 1960s counterinsurgency became the obsession of the Pentagon. The limited war theorists loved it because its political overtones appealed to their highly circumscribed understanding of military power and they thought it a means to wage war without risk of escalation. “Systems analysts” like McNamara loved it because they thought that its complicated precepts (remember, counterinsurgency is the “graduate level of warfare”) were amenable to statistical control. Even the Army embraced it wholeheartedly because they considered it to be their deliverance from the doctrinal wilderness in which they were lost; the Army had finally found a raison d’être. Hindsight clearly added a sense of bemusement to Summers’ comments about the issue:

Twenty years later, it is hard to envision the force with which the concept of counter insurgency struck the Army … Some appreciation of the effect can be gained from such publications as the March 1962 issue of Army, the influential publication of the Association of the U.S. Army, which was devoted to (in its own words) “spreading the gospel” of counterinsurgency. Reading it today sounds more like the description of a new liturgy rather than a discussion of strategic doctrine. (73)

And they say history doesn’t repeat itself…

This led to an epic mischaracterization of the conflict in Vietnam that would have profound ramifications on how the war was conducted:

The guerrillas in Vietnam did not achieve decisive results on their own. Even at the very end there was no popular mass uprising to overthrow the Saigon government. Their actions fit precisely in Sir Robert Thompson’s definition of partisan warfare – they harassed and distracted both the United States and South Vietnam so that North Vietnamese regular forces could reach a decision in conventional battles. (76)

Part II argues that because of the larger failings in policy and strategy, the U.S. lost sight of a coherent objective and lapsed into a strategic defensive posture. This in itself was not fatal to the war effort; indeed, the containment doctrine by its very nature was defensive, and the Korean War showed that victory was still possible in such circumstances as long as political and military objective were kept in harmony. The problem was that due to its own convoluted policy the U.S. never realized that it was on the strategic defensive so it never adopted the military plans that would make such a policy work. Instead, it continued with its tactical offensives against the guerrillas in the South, mistaking the guerrillas for the enemy main effort when they were little more than adjuncts for North Vietnam’s larger strategy:

While a strategic offensive against North Vietnam may not have been politically feasible, we could have taken the tactical offensive to isolate the battlefield. But instead of orienting on North Vietnam – the source of the war – we turned our attention to the symptom – the guerrilla war in the south. Our new “strategy” of counterinsurgency blinded us to the fact that the guerrilla war was tactical and not strategic. It was a kind of economy of force operation on the part of North Vietnam to buy time and to wear down superior U.S. military forces. (88)

A military strategy reconciled to a defensive orientation was perfectly feasible and would have involved U.S. forces deployed along the 17th parallel, extending across Laos (the neutrality of which was a myth) to the Thai border, thereby sealing off South Vietnam and preventing communist infiltration from the North. Meanwhile, counterinsurgency would be the primary responsibility of the ARVN with occasional support from U.S. forces. This strategy would have leveraged the conventional capabilities of the U.S. military and delegated counterinsurgency functions to the forces best suited for them: the locals. Both ARVN and U.S. officers, including Westmoreland, floated plans of this sort at various times but all were rejected. Westmoreland’s 1967 proposal was rejected by President Johnson because he was afraid it would require the mobilization of the reserves, something he was politically unwilling to do. So instead, the U.S. continued to waste its power against the guerrillas in the South and the North simply inserted new cadres when necessary to keep the guerrilla effort alive while it built up its regular forces in the sanctuary of its own territory, preparing for the day when they could launch a full-scale invasion. To apply some of RADM J.C. Wylie’s ideas, the North controlled the critical strategic weights, allowing them to keep the center of gravity (Wylie’s definition of “center of gravity” differs from that of Clausewitz) in South Vietnam, giving them control of the pattern of the war. Their strategy was sound.

The North Vietnamese were on the tactical defensive as part of a strategic offensive to conquer South Vietnam. Our adoption of the strategic defensive was an end it itself and we had substituted the negative aim of counterinsurgency for the positive aim of isolation of the battlefield. This was a fatal flaw. As Clausewitz said, “A major victory can only be obtained by positive measures aimed at decision, never by simply waiting on events. In short, even in the defense, a major stake alone can bring a major gain.” The North Vietnamese had a major stake – the conquest of Indochina. It was the United States that was “simply waiting on events.” (121)

North Vietnam had one objective throughout the war, the conquest of the South, and it pursued the strategic offensive at all times, switching back and forth between the tactical defensive and the tactical offensive. Communist forces assumed the tactical offensive and waged regular warfare in 1965, in 1968 during the Tet Offensive, in the 1972 Eastertide Offensive, and finally in the Ho Chi Minh Campaign of 1975. “Saigon did not fall to barefoot black-pajama-clad guerrillas. It fell to a 130,000-man 18-division invasion force supported by tank and artillery.”(xiii) Unfortunately, the U.S. obsession with counterinsurgency left the ARVN poorly trained and equipped for the communist blitzkrieg that finally ended the war.

General [Van Tien] Dung’s account of the North Vietnamese final offensive read like a Leavenworth practical exercise on offensive operations. His selection of the “center of gravity” could have come directly from Clausewitz: “The basic law of the war,” said General Dung, “was to destroy the enemy’s armed forces, including manpower and war material … the main target of our forces was the [South Vietnamese] regular army.

The communists were master propagandists of “People’s War” rhetoric but they had the correct understanding of the relationship between regular and irregular warfare, the latter being a valuable, but subordinate, complement to the former. For the U.S., “it was not until after the war had already been lost on the American homefront that we put counterinsurgency in proper perspective as a valuable adjunct to our military operations against North Vietnam.” (175)

Elsewhere in Part II, as Summers analyzes other U.S. errors, he makes some comments that have an ominous echo in the present day:

Observers have faulted our intervention in Vietnam as evidence of American arrogance of power – attempts by the United States to be the World’s Policeman. But there is another definition to American arrogance, the international version of our domestic Great Society programs where we presumed that we knew what was best for the world in terms of social, political, and economic development and saw it as our duty to force the world into the American mold – to act not so much the World’s Policeman as the World’s Nanny. It is difficult today to recall the depth of our arrogance. (171)

Difficult in the early 1980’s, when Summers wrote those words…not so difficult today.

Another comment from later in the same chapter:

Our [counterinsurgency] doctrine failed to clearly differentiate between what a beleaguered nation could and should do for itself and the limits of assistance and outside power could provide. Failure to understand and apply these differences led the United States to involve itself in nation building tasks that only the South Vietnamese could ultimately accomplish and diverted our attention from the tasks that were within our capability. (174)


Summers’ argument is not perfect. In my opinion, it has two principle weaknesses. First, while he places counterinsurgency in the proper strategic context, he tends to understate its difficulty. There is a blithe sense in his writings that once North Vietnamese infiltration was cut off all would be well in the South. This would probably be true in the long run, but in the short term, a very intense COIN effort would be required to clean out all the guerrilla cadres. In the Malayan emergency, where the guerrillas had no access to external support, this process took twelve years. I doubt that the government of South Vietnam would have been able to manage without significant American support; to secure victory, U.S. forces would have had to do much more than simply man the frontier with North Vietnam.

Second, and related to the first criticism, Summers places too much faith in the government of South Vietnam by arguing that once the infiltration was halted all of Saigon’s internal woes could be overcome:

Elaborating on this, former I Corps commander Lieutenant General Ngo Quang Truong said that in hindsight halting infiltration was the most critical requirement. He believed that South Vietnam could have solved its internal problems if the infiltration could have been brought under control. Once that had been stopped, everything else would have been “easy.” General Truong’s comment is telling. As he said, “South Vietnam could have solved its internal problem if the infiltration could have been brought under control.” … What the United States could never do was “solve the internal problems” of South Vietnam. Only the Vietnamese themselves could accomplish that task. (170)

The latter part of this comment is manifestly true, but the first part seems a bit of a stretch. The ARVN was a bright spot, but the rest of South Vietnam was a such a basket case that it might have collapsed even in the absence of a communist threat. Cutting off infiltration and defeating the insurgency were prerequisites to improving the situation but they alone would not have been sufficient to cure Saigon’s ills. In a sense, the mortal blow to the American war effort came not with the Tet Offensive of 1968, but with the death of Ngo Dinh Diem in 1963. He certainly was not a liberal democrat (what else is to be expected in post-colonial Indochina?), but he was the only South Vietnamese leader that had a realistic chance of securing his writ across the country. If the U.S. was serious about winning the war it should have kept him in power. Too bad Kennedy had him killed instead.


To sum up, there are three reason why every sentient being in the universe should read On Strategy. First, it is probably the most cogent analysis of the American defeat in Vietnam that has ever been written. That alone makes it required reading. Second, it places such fad concepts as counterinsurgency and nation building in the proper context as tactical adjuncts to the larger strategic war effort. This point is especially important today, for obvious reasons. Third, it is a very interesting application of Clausewitz. Summers doesn’t just decorate the book with quotes from the Prussian Master; the entire analysis is conducted from within the framework of On War. Some could argue with a few of his interpretations of Clausewitz, but the way he applies them to Vietnam is quite brilliant. Short of meeting him in the afterlife we will never know what Clausewitz would say about the Vietnam War. Thanks to Col. Summers, however, we at least have a pretty good idea.

Similarly, Col. Harry Summers died in 1999, depriving the world of valuable commentary concerning America’s ongoing wars. It’s fair to say that he would be horrified by the extent to which COIN has come to dominate our military and strategic thinking. What he understood and argued so forcefully was that “a war is a war is a war.” Regular warfare, irregular warfare, and counterinsurgency are simply tools that, when applied absent a strategic context that includes the mobilization of political will, are not only useless, but outright dangerous.


3 thoughts on “Clausewitz on Vietnam: The Summers Thesis

  1. Pingback: It’s Still Wednesday: Assorted Miscellany « The Committee of Public Safety

  2. Concerning Ngo Dinh Diem—“Too bad Kennedy had him killed instead.”
    How can you prove that Kennedy “had him killed”?

    • The Kennedy administration orchestrated the coup that resulted in the murder of Ngo Dinh Diem. At the time, the U.S. assumed that it could only win the war with different leadership in Saigon, so it went about arranging that change in leadership. Every single history of U.S. policy during the Vietnam War supports this point, but for starters, I will direct you here:

      Apologists for JFK often argue that, though he was aware of the coup, he did not intend for Diem to die in the process. Supposedly, Kennedy was disturbed upon learning of Diem’s death. That seems extremely naive to me; Third World coups are very messy affairs…it should have been obvious that Diem would die as a result. It’s more likely that the point is political spin to prevent the muddying of JFK’s deific legacy.

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