This is a book about past wars. No, it’s a book about present wars. No, actually, it’s a book about future wars. Or it’s a book about your imagination.

Every War Must End by the late Fred Charles Iklé is a book for considering war – this one, that one, and the one we haven’t had yet. Iklé, who passed away in 2011, served as undersecretary of defense for policy in the Reagan administration. For him, the essential lesson is that it is much easier to start a war than successfully to conclude one. Having achievable aims – both military and political – and stopping when they have been met is key to success. The alternative is to slog along with grinding casualties until the conflict peters out ignominiously when public opinion no longer supports the effort. The French, he pointed out, were the military victors in Algeria – as were the Americans in Vietnam – but in both cases, the Western power withdrew without a political victory, and public disillusionment hampered the government at home and abroad for years after.

Think of Afghanistan, except we haven’t withdrawn yet.

Iklé’s examples are primarily World War I, World War II, and Korea, with a bit of the Russo-Finnish and Vietnam wars thrown in. The elapsed decades make it easier to dissect them and their lessons with less emotion. But your head will have trouble not making the leap to current wars – and that’s OK.

Lesson 1: Meticulously detailed reports are not a substitute for unsubstantiated assumptions or failing to articulate political and military objectives and how to achieve them.

The German high command planned in painstaking detail for unrestricted submarine warfare against the British toward the end of World War I. Berlin knew how much of what the British imported and on how many ships. Planners knew what the British considered essential items and when those would run out. But from the detailed dive into measurements, the Germans made a strange leap into political/patriotic/emotional imponderables. They assumed that the British people would force the government to fold in five months – before the Americans had an opportunity to bring their resources fully to bear. The British didn’t. The Americans did. The Germans lost.

Similarly, when the Japanese were planning the attack on Pearl Harbor, they made meticulous counts of hardware, fuel and personnel. But their understanding of how the war would end was hazy. Iklé notes that, in a memorandum, the service chiefs wrote:

It is very difficult to predict the termination of a war, and it would be well-nigh impossible to expect the surrender of the United States… At any rate we should be able to establish an invincible position…Meanwhile, we may hope that we will be able to influence the trend of affairs and bring the war to an end.

The Navy Chief of Staff told the Emperor:

Even if our Empire should win a decisive naval victory, we will not thereby be able to bring the war to a conclusion…Our Empire does not have the means to take the offensive, overcome the enemy and make them give up their will to fight.

Lesson 2: Failure to articulate an achievable objective may lead to side discussions, including when and how to start the fighting, but rarely leads to steps to de-escalate the crisis. Lesson 2A: And once the war begins, the fighting is often subject to forces other than an evaluation of the most advantageous way to stop it, either for the side that is winning to consolidate its gains, or for the side that is losing to minimize the damage. Lesson 2B: War aims may change radically during the fighting.

Even after understanding that the Japanese military a) could not assume/assure victory or b) even envision the end of the war, the Japanese leadership, including the Emperor, chose not to press the point. Instead, they engaged in discussions of when to strike Pearl Harbor, not whether. The Germans had the same conversation about the timing, not the value, of unrestricted submarine warfare.

Once war starts, Iklé notes, the public has a say in ending it – and the public’s view may not coincide with that of either the military or civilian leadership.

Fighting sharpens feelings of hostility. It creates fears that an opponent might again resort to violence, and thus adds to the skepticism about a compromise peace…More is expected of a settlement because both the government and the people will feel that the outcome of the war ought to justify the sacrifices (already) incurred.

Lesson 3: “Appeasement,” and “Ending Wars before they Start” are not the same thing, but Iklé thinks they’re close. He tries to resurrect the reputation of “appeasement,” but in one of the few miscues in the book, he fails.

Prior to the late 1930s, “appeasement” did not mean feeding the appetite and power of an aggressor, but pacifying through concessions a conflict that threatened to erupt into a war. For the present era, it is critically important to understand how appeasement can succeed or fail, without being swayed by false lessons from the 1930s.

It is hard to understand the difference between “pacifying through concessions” and “appeasement.” Is there a point at which the party reaping the concessions decides, “This is enough. I don’t really need any more, so I’ll stop threatening the neighbors.” Or does that party think, “Well, I’ve gotten this much without too much trouble. I think I’ll go for more.” Considering Israeli concessions to the Palestinian Arabs since the 1993 Oslo Accords doesn’t help, nor does the 2015 Joint Comprehensive Plan of Action (the Iran deal), or watching China build militarized islands in the South China Sea, or watching Russia reclaim Crimea.

Churchill said, “Appeasement is one feeding the crocodile in hopes that it will eat him last,” not that the crocodile will not eat him at all. Churchill wins this point.

Lesson 4: It isn’t always the political forces looking for terms against military officers looking for war. More than once, Iklé points out, it is the military that has a better understanding of the costs that will be imposed by starting or continuing a war. Finnish military chief – and later Finnish president – Carl Gustav Emil Mannerheim opted out of Finland’s alliance with Germany to make a separate peace with Russia in 1944:

I wish especially to emphasize that Germany will live on, even if fate should deny you victory in your fighting. Nobody can give such an assurance regarding Finland. If this nation of barely 4 million be defeated militarily, there can be no doubt that it will be driven into exile or exterminated. I cannot expose my people to such a risk.

If you’re starting to think about Israel here, hold on. In the chapter “The Search for an Exit,” Iklé considers how countries finally see the end coming and make the necessary changes to policy. Think about Palestinians instead.

To make peace may require that the nation get rid of its leader. But the leader, in seeking advice from his ministers on how to end the war, cannot ask for a frank debate on his own political demise. Or, to make peace may require the abandonment of war aims for which men are still being asked to die. If the leaders who wish to argue for such a peace denigrate these war aims, they would be asserting that the men at the front are dying in vain. To make peace may require disbanding the existing army (or conversely, letting it rule the country). But the civilian and military leaders in deciding how to end the war cannot have a frank debate on how to abolish each other.

Is it possible for Mahmoud Abbas to abandon the war he has been stoking for more than a quarter century? Iklé wrote of Mussolini:

Mussolini (did not argue) that he would remain on “the world scene” or that the military situation was better than his chief of staff told him. But under the stress of mounting catastrophe he could not muster the determination to choose a policy that would have corresponded to the military situation. So painful had the facts become that he could no longer face them.

Abbas, again.

Finally, then, is Lesson 5: This slim volume will take you places you may not have planned to go. You will read about the Korean War and think about Kim Jong Un or read about Nazi Germany and think about Palestinians. (No, NOT because they are the same, but because some of the same logic that applied to Germany entering a war that it could not conceive of winning applies to Palestinian decision making.) Iraq, ISIS, Iran, and Afghanistan will begin to populate the pages along with the Finns, Russians, Germans, and Algerians. You will compare Charles DeGaulle to Lyndon Johnson to Barak Obama in Iraq and Afghanistan. You might find yourself asking what we’re still doing in Afghanistan 17 years, more than 2,700 Americans dead, more than 360,000 Afghans killed directly and indirectly, and about a trillion dollars later. What is the military objective, and how has President Trump improved on the Obama recipe?

That would be a useful thing.

The book is also a reminder that as long ago as perhaps 400-180 BCE, Ecclesiastes – attributed to King Solomon – was writing, “The thing that hath been, it is that which shall be; and that which is done is that which shall be done: and there is no new thing under the sun.” (“Ain chadash tachat hashamayim.”)

Reprinted with author’s permission from Jewish Policy Center