ZONNEBEKE, Belgium — To walk the orderly rows of headstones in the elegant graveyards that hold the dead of World War I is to feel awe and distance. With the death of the last veterans, World War I, which began 100 years ago, has moved from memory to history. But its resonance has not faded — on land and geography, people and nations, and on the causes and consequences of modern war.

The memorial at Tyne Cot, near Ypres and the muddy killing ground of Passchendaele, is the largest British Commonwealth cemetery in the world. Nearly 12,000 soldiers are buried, some 8,400 of them identified only as “A Soldier of the Great War, Known Unto God.” Despite the immensity of this space, the soldiers represent only a tiny portion of the 8.5 million or more from both sides who died, and that number a fraction of the 20 million who were severely wounded.

In Europe’s first total war, called the Great War, 7 million civilians also died.

Yet the establishment of these grave sites and monuments, here and in villages all over the Western Front, is more than a reminder of the scale of the killing. World War I also began a tradition of memorializing ordinary soldiers by name and burying them alongside their officers, a posthumous recognition of the individual after the trauma of mass slaughter.

Save 75% on a Digital Subscription Today

World War I could be said to have begun in Sarajevo on June 28, 1914, with the assassination of Archduke Franz Ferdinand and his wife, Sophie, by a 19-year-old Serbian nationalist, Gavrilo Princip, who was seeking a greater Serbia. The 4½ years that followed, as the war spread throughout Europe, the Middle East and Asia, reshaped the modern world in fundamental ways.

The war destroyed kings, kaisers, czars and sultans; it demolished empires; it introduced chemical weapons, tanks and airborne bombing; it brought millions of women into the workforce, hastening their legal right to vote. It gave independence to nations such as Ukraine, Poland and the Baltic countries and created new nations in the Middle East with often arbitrary borders; it brought about major cultural changes, including a new understanding of the psychology of war, of “shell shock” and post-traumatic stress.

It also featured the initial step of the United States as a global power. President Woodrow Wilson ultimately failed in his ambitions for a new world order and a credible League of Nations, setting off much chaos with his insistence on an armistice and his support for undefined “self-determination.” And the rapid retreat of the United States from Europe helped sow the ground for World War II.

Emotional legacies

Historians still squabble over responsibility for the war. Some continue to blame Germany, and others depict a system of rivalries, alliances and anxieties, driven by concerns about the growing weakness of the Austro-Hungarian and Ottoman empires and the growing strength of Germany and Russia that was likely to produce a war in any case, even if there was some other casus belli.

But the emotional legacies are different for different countries. For France the war, however bloody, was a necessary response to invasion. Preventing the German army from reaching Paris in the first battle of the Marne spelled the difference between freedom and slavery. The second battle of the Marne, with the help of U.S. soldiers, was the beginning of the end for the Germans. This was France’s “good war,” while World War II was an embarrassing collapse, with significant collaboration.

For Germany, which had invested heavily in the machinery of war, it was an almost incomprehensible defeat, laying the groundwork for revolution, revanchism, fascism and genocide. Oddly enough, says Max Hastings, a war historian, Germany could have dominated Europe in 20 years economically if only it had not gone to war.

“The supreme irony of 1914 is how many of the rulers of Europe grossly overestimated military power and grossly underestimated economic power,” Hastings said, a point he now emphasizes when speaking with Chinese generals. The Germans, too, are still coming to terms with their past, unsure how much to press their current economic and political strength in Europe.

For Britain, there remains a debate about whether the British even had to fight. But fight they did, with millions of volunteers until the dead were mounded so high that conscription was finally imposed in 1916. The memory of July 1, 1916, the first day of the Battle of the Somme — when 20,000 British soldiers died, 40,000 were wounded and 60 percent of officers were killed — has marked British consciousness and become a byword for mindless slaughter.

“The sense that the war was futile and unnecessary still hangs over a lot of the discussion in Britain,” said Lawrence Freedman, professor of war studies at King’s College London.

In Britain there is also a deep presumption that the generals were incompetent and cold to human sacrifice, that “lions” — the brave ordinary Tommies — were “led by donkeys” like Field Marshal Douglas Haig.

“That was almost certainly true at the start, but not true at the end,” Freedman said. “But the notion that lives were lost on an industrial scale because generals kept trying to launch offensives for a few feet of ground is widespread.”

In fact, the beginning of the war was mobile and extremely bloody, as were the last few months, when the big offensives of 1918 broke the German army. The rate of killing in the muck and mud of the trenches was much lower than during the mobile part of the war.

Finding the lessons

The war still casts a long shadow, refracted through what can now seem the inevitability of World War II and our tumultuous modern history. This is also, after all, the 75th anniversary of the start of that war and the 25th anniversary of the collapse of the Berlin Wall.

The end of the Cold War was in a sense a return to the end of World War I, restoring sovereignty to the countries of Eastern Europe, one reason they are so eager to defend it now.

Analysts wonder if the period of U.S. and European supremacy itself is fading, given the rise of China and the return of traditional nationalism, not just in Russia but in the many euroskeptic voters in France, Britain and Denmark.

Some question whether the lessons of 1914 or of 1939 are more valid today. Do we heed only the lessons of 1939, when restraint was costly, and miss the lessons of 1914, when restraint could have avoided the war?

Some see a continuing struggle between Germany and Russia for mastery of Europe, a struggle that marked both world wars.

Others point to the dangers of declining powers faced with rising ones, considering both China and the Middle East, where the Syrian civil war and the advance of Islamic militants toward Baghdad are ripping up the colonial borders drawn up in the Sykes-Picot pact reached by the French and British, with Russian agreement, in 1916, the middle of World War I, when the Ottoman Empire was cracking.

Even the Balfour Declaration, which threw British support behind the establishment of a Jewish state in Palestine, was signed during the war, in November 1917.

With the new interest in the centenary, mourners and tourists, schoolchildren and relatives, walk the battlefields of Ypres, which still turn up human remains and live ammunition. And they walk the finely kept grass between the gray headstones at Tyne Cot, laying bright red poppies upon the earth.

Not far away from Tyne Cot is the tiny Flanders Field American Cemetery and Memorial, an exquisitely kept 6 acres containing only 368 graves, including 21 unknown, while the names of 43 more, missing in action, are carved on the walls of a small chapel.

If Tyne Cot is the largest military cemetery for the Commonwealth, this is the smallest U.S. military cemetery.

The headstones tell the stories of first- and second-generation Americans, their names redolent of the Europe their parents left to make a better life, who returned here to die. Like Giuseppe Spano, a private from Pennsylvania, and Angelo Mazzarella, a private from West Virginia, and Emil P. Wiser, a private from Montana, and Ole Olson, a private from Wisconsin, and John Dziurzynski, a private first class from Ohio.

“The dead were and are not,” historian G.M. Trevelyan wrote in his autobiography. “Their place knows them no more and is ours today. Yet they were once as real as we, and we shall tomorrow be shadows like them.”