World War I: why it still matters: in 1919, the 'war to end all wars' formally ended with The Treaty of Versailles. But 90 years later, we're still living with the consequences.

• Author: Whitney, Craig R.
• Position: TIMES PAST

World War I, the most murderous conflict in history up to that time, came to a halt with a cease-fire at 11 a.m. on the 11th day of the 11th month of 1918. In four years, 16 million people had died, centuries-old empires and dynasties had come crashing to the ground, and economic and political chaos had overtaken much of the globe.

Sadder still, the "War to End All Wars" proved anything but. The Treaty of Versailles may have formally ended the war in June 1919, but 90 years later, the war's consequences are still being felt around the globe: The war in Iraq, the conflict between Israel and the Palestinians, and tensions with Russia are just a few of the foreign-policy challenges on President Obama's plate whose roots go back to World War I and its aftermath.

The war began in 1914 with the assassination of the heir to the throne of the Austro-Hungarian empire, Archduke Franz Ferdinand, which drew the great powers of Europe, entangled by all sorts of complex alliances, onto the battlefield.

After staying neutral for three years, the United States entered the war in 1917 to "make the world safe for democracy," as President Woodrow Wilson put it, and to come to the aid of Britain and France in their struggle against Germany, Austria-Hungary, and the Ottoman Turks.

When it was over, the victorious Allies set about trying to prevent future global conflicts, to punish their enemies, and, with the demise of the Austro-Hungarian and Ottoman Empires, to redraw the maps of Europe, the Middle East, and even Asia.

You've probably read in your history textbooks about the war's most immediate consequences: Wilson advocated for his "Fourteen Points," which called for, among other things, an end to colonialism (which the British and French mostly ignored), and a League of Nations, the first international body dedicated to keeping the peace.

ANOTHER WORLD WAR

But Wilson was incapacitated after suffering a stroke, and the U.S. Senate refused to approve American participation in the League, which rendered it toothless. It was replaced in 1945 with the United Nations.

The harsh terms that Versailles imposed on Germany after the war, including billions of dollars in reparations to make it pay the cost of the conflict, decimated the nation's economy. In the 1920s and '30s Adolph Hider capitalized on Germany's humiliation to bring the Nazi party to power.

The result was World War II, which began in 1939, and the systematic murder of millions of innocent Europeans, including 6 million Jews, who Hitler blamed for many of Germany's problems.

Here's a look at some of the other consequences of World War I that you may be less familiar with, and that lie behind many of the headlines we see today.

IRAQ

Before World War I, the Ottoman Empire spanned southeastern Europe, North Africa, and the Middle East. After the war, the League of Nations gave "mandates" over parts of the Mideast to France and Great Britain that suited the interests of Paris and London, but ignored the wishes of most of the people who actually lived there. In Mesopotamia, the Ottoman territory that became Iraq, the British cobbled together the provinces of Baghdad, Basra, and Mosul, whose people--Shiites, Sunnis, and Kurds, respectively--were as much at odds with each other in 1919 as they are today. (The Shiite and Sunni sects of Islam had split centuries earlier over who would succeed Muhammad as Islam's leader.)

"In 1919," according to historian Margaret MacMillan, "there was no Iraqi people: History, religion, geography pulled the people apart, not...