THE WAR THAT ENDED PEACE. By Margaret MacMillan. Random House. 784 pages. $35.

JULY, 1914. By Sean McMeekin. Basic Books. 480 pages. $29.99.

CATASTROPHE 1914: Europe Goes to War. By Max Hasting. Knopf. 672 pages. $35.

THE SLEEPWALKERS: How Europe Went to War in 1914. By Christopher Clark. Harper. 736 pages. $29.99.

Editor's Note: One hundred years ago on July 28, the Great War began. It was a conflict that changed the world in profound ways. We mark the anniversary with a review of four recent books.

Commemorations of the centennial of The Great War of 1914-18 are naturally leading to an outpouring of books on the subject. Because this war is now almost universally recognized to have been unnecessary and long-known to have been appallingly destructive, the vexed question continues to be: Why did major European powers go over the edge in 1914?

The four books reviewed here represent recent efforts in English to provide answers to citizens who should want to know. A close study of the outbreak of World War I carries even greater importance today in light of the eerie similarities between the global crises of the early 20th and early 21st centuries.

Most credible historians can be classified as either "splitters" or "lumpers." Splitters marshal as much factual evidence as possible because they see major historical events as dependent on a great many contingencies. Splitters draw conclusions, but they can bury them in a mass of details. Lumpers also work through large amounts of evidence, but they are more willing to make decisions about the central factors that cause major events. Lumpers can sometimes overstate their conclusions or downplay important evidence. The four works under review illustrate these two approaches.

'The War That Ended Peace'

Margaret MacMillan is a splitter. Devoted readers of her 700-page "The War That Ended Peace" will be rewarded with a panoramic, deeply contextual, chronological march through the 25 years before 1914. MacMillan understands how to do scholarly historical research, read deeply and widely among reliable primary and secondary sources, and draw measured conclusions based on evidence. The book contains dozens of nicely explained photos and illustrations, scores of entertaining anecdotes, and hundreds of extensive quotations, in addition to mini-biographies of all major emperors, kings, ministers, foreign secretaries, ambassadors and generals along with their families and long-forgotten staff underlings.

Readers who prefer to skip around can do so because each graceful chapter can be read as a stand-alone set-piece. At the same time, the massive amount of detail and the insistence on a chronological approach means that the reader can lose sight of the overall analysis. Serbia, for example, the country at the center of the 1914 crisis, is not seriously discussed until after page 400, and the powder-keg Balkan states and their wars do not appear until page 467.

A shorter book would have eliminated digressions that are often tangential to her intriguing question: Why did peace not continue in Europe in 1914 as it had, by and large, since Napoleon's defeat in 1815? Her answers, in brief, are that this big war could have been avoided. The handful of leaders who decided the fate of hundreds of millions all had choices.

However, the crisis that started because of the assassination of the Archduke of Austria-Hungary on June 28, 1914, escalated just five weeks later in a general war. MacMillan's book leads to the conclusion that the big powers, acting aggressively, faced more and more diplomatic and military crises of their own making. Each crisis taught lessons. By 1912, all big powers shared a narrow set of views that made a big war very possible: leaders were too fearful of military threats, (all powers), too obsessed with appearing weak against rivals (Russia, Austria), too worried about national decline (Russia, Austria), too worried about rising rivals (Britain, Germany), too willing to accept uncritically the advice of generals (Russia, Austria, Germany, France), and civilians were too uninformed about how military plans limited diplomatic options (all major powers).

By 1914, all sides praised the soldier as above criticism and promoted the military values of self-sacrifice, hierarchy, discipline and order in civilian society. Oddly, weaker allies ended up dictating to the more powerful. The Germans, for example, were too fearful of losing their Austro-Hungarian ally. The British and the French, each separately, were too fearful of losing their Russian ally. The Russians, not wanting to appear weak to the Austrians and Germans, stood with the Serbian Slavs. Worst of all, leaders on all sides suffered from a failure of imagination on how destructive war would be and a lack of courage to say no to the many war hawks among their advisers.

European generals learned from Napoleon of the superiority of offensive warfare. The American Civil War taught that greater manpower and material won wars. The French, following mainstream military thinking, calculated that two battalions would always defeat one battalion because they could fire more bullets.

Contrary to the stereotype, generals on all sides knew that the next war could be a long one, which frightened them. They expected that major social upheavals would occur because food supplies would run out and no country had the wealth to supply titanic-sized armies for very long. Thus, German generals devised the ambitious eight-stage Schlieffen Plan to overwhelm France in 40 days, then defeat Russia. Even if Britain joined the French, the Germans believed that a small British army would make no difference. There was no military Plan B.

Leaders on all sides took the same stance: We do not want a war and will not start one, but we will fight one if pushed. In the final hours, all sides made sure that their citizens believed that each country had no choice but to defend itself and its allies against belligerent, unreasonable enemies.

'July, 1914'

Sean McMeekin, a splitter, focuses in his "July, 1914" on the six most-studied weeks in European history, June 28 to Aug. 4. As a professional historian, he has scoured the diplomatic exchanges and decoded telegrams and memoirs. He focuses on a few dozen leaders who made the decisions.

McMeekin takes us into secret meetings, embassies, yachts, palaces and anywhere else where key leaders exchanged information. For him, the telegrams and informal conversations matter down to the day and hour. He wants to figure out which of the countries was most responsible for the tragedy. Each power (and Serbia, too) bears responsibility, but not equally. He points the finger at Russia and France.

The French, eager to have Russia fight Germany in the event of war, convinced the Russians that France would unconditionally support Russia in its stand against Austria. The Russians for their part unnecessarily escalated tensions by mobilizing their army and denied the fact for several days to the Austrians and Germans, making both deeply suspicious of Russian intentions and triggering Germany to mobilize. Austrian ministers fatefully made impossible demands on the national sovereignty of Serbia.

'Catastrophe,' 'Sleepwalkers'

The last two books under review, Max Hasting's "Catastrophe 1914" and Christopher Clark's "The Sleepwalkers," are by, respectively, an ambitious amateur historian and a professional academic. Clark teaches at the University of Cambridge and writes for a scholarly audience, while Hastings is a public intellectual aiming for a broader, educated readership.

Clark is a splitter, and his 560-page tome is full of details of the six-week crisis that led to war and is strongly anchored in English and German language sources.

Hastings is a lumper. His work covers the entire second half of 1914 and relies on memoirs and recent scholarly debates to identify several big themes that shaped decision-making in 1914.

Clark's detailed description of the weeks that led up to the war is supplemented by an account of the alliance system that linked the major European powers together. Reading deeply in English, French and German primary sources, Clark argues that it is futile to place blame for the war on one country or a few individuals. Like MacMillan, Clark argues that the cumulative decisions of many men across Europe over a period of weeks made peace less and less likely.

A key player in the crisis is Dragutin Dimitrijevic (often known as Apis), the shadowy director of Serbian military intelligence and representative of the most aggressive vision of Serbian nationalism, which assumed that violence and terror had to be used to unite all Serb speakers in one country. It seems likely that he coordinated the conspiracy that resulted in Gavrilo Princip assassinating Archduke Franz Josef on June 28, 1914, in Sarajevo.

Over the next several weeks, leaders of the major powers dissimulated and schemed, slowly coming to the conclusion that a war was better now than later, and the Sarajevo assassination was as good a reason for it as any, Clark says. Everybody in a position of power looks culpable, so it is pointless to assign blame. Powerful men had the chance to make the case for peace. The fact that they did not made the 20th century much worse than it need have been.

Clark's and MacMillan's books demand a great deal from the reader. There are insights aplenty but they come only with patience and concentration.

Hastings wants to capture a wide audience. He is horrified at the violence of the war and mortified that leaders opted to fight when they could have chosen peace. He believes, however, that a number of important deductions can be made about 1914.

Taking issue with the vast majority of scholars, he argues that the war had to be fought. A victorious Germany would have imposed some vision of a federal Europe that would have been far worse than the current European Union (of which he is deeply skeptical). Secondly, Hastings especially tries to rehabilitate British generals, who were, in fact, quite intelligent, learned from their mistakes, and did the best they could in an impossible situation, Hastings argues.

In other words, according to Hastings, we need to know about World War I because sometimes you have to fight an unpopular war. It is perhaps not surprising that this book is a best-seller.

All four authors agree that what happened in 1914 still matters today, and that current policy makers can learn from the choices made by men of that era. What are the uses of this history for citizens in a 21st century democracy?

On one level, these authors share the view that the problems of the past can help us understand and deal with the problems of the present. On another level, they reveal how history is studied. People often use the past to define themselves as good and people they do not like as bad. This is certainly the case for Hastings: Imperial Germany stands in for the European Union, and Prime Minister Lloyd George may have been a cynical political manipulator, but he knew how to fight and, along with Douglas Haig, did not flinch from sending one million British and Empire troops to their deaths by Nov. 11, 1918.

He provides villains and heroes, and this is sometimes what many of us are understandably looking for. Professional scholars, on the other hand, are more inclined to study individuals in the past as those people saw themselves and to analyze the circumstances that shaped them and that they shaped by the choices they made.

World War I is one of the best cases yet for exploring how wars that no one wants can start, how unpredictable they can be and how they can unleash profound changes that no one can imagine.

Reviewer Bryan Ganaway is a faculty Fellow at the Honors College and Director of the International Scholars at the College of Charleston. Reviewer Bill Olejniczak teaches modern European history and directs the European Studies program at the College of Charleston.