How states stop the wars they start

Cover Interview of

In a nutshell

How Wars End starts with Carl von Clausewitz’s famous insight that war is politics by other means. War is not just an exercise in martial engineering, two waves of soldiers and war machines crashing against each other. Rather, war is a fundamentally political act. States start wars to accomplish political goals.

But, a state will only use the tool of war to accomplish political goals if the costs of fighting do not exceed the expected gains, and if the state is confident that it can accomplish its goals. As the costs of war escalate and its confidence in winning declines, a belligerent will try to end its war.

There’s a big catch to the idea that rising costs and declining prospects of victory will push a state to end a war. That portrayal assumes that belligerents are confident that once war ends, each side can return to peace. Sometimes, a belligerent doesn’t trust its adversary to abide by a war-ending peace settlement. The belligerent fears that the adversary might bide its time after peace is struck and launch a surprise attack when the opportunity presents itself. A belligerent fears an adversary who will pose this kind of long term threat to its security. Under these circumstances, belligerents may ignore the costs of war and doubts about ultimate victory, and instead pursue the decisive defeat and unconditional surrender of the adversary. Accomplishing this kind of total victory allows the belligerent to annex the adversary, occupy its territory, and/or impose regime change. Doing so solves the distrust problem, as the adversary wouldn’t be able to break a war-ending peace agreement.

So this book provides a general explanation of how wars end. It is also the first book to answer the big historical question: When do belligerents agree to end a war before one side has been completely defeated, and when do belligerents try to achieve absolute victory and inflict unconditional surrender?

“War is a fundamentally political act. States start wars to accomplish political goals.”

The wide angle

I started thinking about this book in the early 2000s. On the policy side, in 2002 the George W. Bush administration announced the National Security Strategy, sometimes called the Bush Doctrine, which declared, among other things, that the United States could not trust rogue states to abide by their international commitments to eschew weapons of mass destruction and links to terrorist groups. Facing these new threats, the U.S. would reserve the option of attacking and overthrowing these regimes. This policy was the intellectual foundation of the 2003 decision to invade Iraq. The assumption was that Saddam Hussein had violated and would violate United Nations Security Council Resolutions to abandon weapons of mass destruction, and so the only solution was to oust him from power.

In the book, I develop a general argument which helps put the Bush Doctrine into a larger context. I also talk about whether or not the American national interest is served by launching wars which seek to unseat dictators who support terrorists or who seek nuclear weapons or other weapons of mass destruction.

On the scholarly side, several political scientists around that time talked about this idea that war is political, and were crafting arguments about how leaders end wars when the costs of fighting escalate or the perceived chances of winning diminish. But I noticed that there were lots of wars which seemed to drag on and on even as the costs of war escalated. Furthermore, some belligerents refused to negotiate even as they were clearly losing. These wars struck me as historical puzzles worth exploring.

How Wars End contains case studies from the American Civil War, World War I, the 1939-1940 Winter War between the Soviet Union and Finland, World War II, and the Korean War, offering solutions to several of the historical puzzles in which belligerents fought on even when the costs of war were mounting and the likelihood of victory seemed to be decreasing.

For instance, why didn’t the Confederacy accept President’s Lincoln’s February 1865 peace deal when the war was clearly lost? In early 1918, why didn’t Germany accept peace and a prewar status quo with Britain and France after it had defeated Russia and conquered huge swaths of territory in the East? During World War II, why did Japan refuse to negotiate for years, even though many in the Japanese leadership knew the war was lost as early as the 1942 Guadalcanal campaign? Why, after the North Korean invasion of South Korea, did President Truman decide to pursue the conquest of North Korea before the military tide had turned in the favor of the U.S. and South Korea? Why did Truman then abandon that goal after China intervened in fall 1950? And why did the Korean War drag on in bloody pointlessness for two more years after the front settled into stalemate in 1951?

January 1, 2010

A close-up

The chapter on the American Civil War describes what may have been Lincoln’s finest moment as president. During the summer of 1864, Northern public support for the war was collapsing. If Lincoln did not make a peace deal with the Confederacy, including renouncing the 1863 Emancipation Proclamation which freed the Confederate slaves, he was guaranteed to lose the November presidential election to the anti-war Democrat George McClellan.

But Lincoln refused to negotiate, specifically refusing to budge on the Emancipation Proclamation. The Proclamation had enhanced the Union’s military power by encouraging blacks to fight for the Union and against the Confederacy. Lincoln feared that if he backtracked on the Proclamation, it would inspire the Southern states to break any peace agreement and demand full independence. Such an outcome would, in Lincoln’s mind, lead to the unraveling of the entire Union. Lincoln preferred losing the fall election and sacrificing his political fortune on the altar of freedom to winning a Pyrrhic electoral victory and see his beloved Union become, in the words of his predecessor James Buchanan, “a rope of sand” disintegrating as each state went its own way. Fortunately, General William Sherman’s great victory at Atlanta in September 1864 boosted Union public support for the war, and saved Lincoln’s presidency as well as perhaps the Union itself.

Another fascinating case is Winston’s Churchill’s decision to fight on against Germany in late May 1940. Things looked quite bleak for Britain. France was falling, and Germany was racking up a string of other conquests of Belgium, the Netherlands, Denmark, and Norway. The Soviet Union was at this point a German ally. America was not yet even close to entering the war. Germany appeared poised to invade Britain after conquering France, and Britain’s prospects for fending off such an attack were dim.

Some of Britain’s highest leaders, such as Lord Halifax, urged Churchill to negotiate with Hitler in order to save the country from conquest. But Churchill refused. He thought that Hitler would not abide by any war-ending peace deal. Hitler would demand that Britain hand over its navy and its colonial possessions; after doing so Britain would be at Germany’s mercy. So, because he deeply distrusted Germany, and despite Britain’s precarious position, Churchill decided to take his chances and continue to fight, rather than strike a deal with Hitler.

It was during the months that followed that Churchill gave his most stirring speeches encouraging Britons to fight on: “We shall not flag or fail. We shall go on to the end. We shall fight in France, we shall fight on the seas and oceans, we shall fight with growing strength in the air, we shall defend our island, whatever the cost may be, we shall fight on the beaches, we shall fight on the landing grounds, we shall fight in the fields and in the streets, we shall fight in the hills; we shall never surrender.” More tersely, he also declared, “If this long island story of ours is to end at last, let it end only when each one of us lies choking in his own blood upon the ground.”

“When belligerents fear that the other side will not abide by a war-ending peace settlement, this fear pushes them to reject negotiations and instead pursue the absolute defeat of their adversary.”


Singing Norman Whitfield and Barrett Strong’s famous song “War,” Edwin Starr declared, “War! What is it good for? Absolutely nothing.” Some people argue that war happens because it reflects fundamental aggressiveness in human nature. Some argue that war happens because two countries or societies simply hate each other. And some argue that technology causes war, that once weapons are invented countries seek reasons to use them.

This book provides a different answer to this question, explaining the political function served by war. I argue that countries fight wars to solve problems of mistrust. This is a longstanding observation, that mutual fear causes countries to launch wars. This book expands on past work, arguing that fear also shapes the way that countries fight and end their wars. When belligerents fear that the other side will not abide by a war-ending peace settlement, this fear pushes them to reject negotiations and instead pursue the absolute defeat of their adversary. Eliminating the adversary solves the mistrust problem.

That being said, though adversaries sometimes try to solve their mistrust problems by fighting wars to the finish, the book also provides caveats as to why this is not always an attractive foreign policy. Certainly, sometimes it is the best and only thing to do—the absolute defeat of Germany, Italy, and Japan in World War II being perhaps the best examples. However, sometimes you can inflict total defeat on a rogue leader’s military, but then face a costly insurgency after the conventional war has ended. Think Iraq and Afghanistan. Sometimes you can use other means to deal with mistrust which are much cheaper than fighting a war, and are sufficiently effective. We mistrusted the Soviet Union, but deterrence kept them from attacking America or its allies for decades. And a state which appears to be untrustworthy and dangerous may actually pose much less of a threat than we had thought, thus the costs of a war to oust the leader would not be worth bearing. Iraq’s lack of weapons of mass destruction or connections to terrorist groups stands out as a clear example of this kind of paper tiger.

© 2010 Dan Reiter
Dan Reiter How Wars End Princeton University Press 320 pages, 9 x 8 inches ISBN 978 0691140605 ISBN 978 0691140599

Dr. Dan Reiter is chair of the political science department at Emory University. He received his Ph.D. from the University of Michigan, and served as a post-doctoral fellow at Harvard University. In 2002, he received the Karl Deutsch Award from the International Studies Association, given “annually to a scholar in international relations under age 40, or within ten years of defending his or her dissertation, who is judged to have made, through a body of publications, the most significant contribution to the study of International Relations and Peace Research.” He has published dozens of scholarly articles, as well as Crucible of Beliefs: Learning, Alliances, and World Wars (Cornell, 1996) and Democracies at War (Princeton, 2002; coauthored with Allan Stam).

Cover Interview of
January 1, 2010