Meeting at the site of one of Europe’s most intense battles, French President François Hollande and German President Joachim Gauck took a moment to reflect on how much the continent and the world have changed since the beginning of World War I a century ago.
In a gesture of moving forward, the two leaders of the former enemy nations ended the ceremony by resting a time capsule in the concrete of a museum’s foundation. The capsule holds a letter of peace for future generations.
"France and Germany's history proves that determination can overcome fatality," Hollande said at the event, "and that two people who were viewed as hereditary enemies can, within a few years, reconcile."
World War I is one of history's deadliest conflicts. Sparked by the shooting of Archduke Franz Ferdinand of Austria in 1914, the Great War was fought by 28 countries and cost more than $200 billion at the time.
More than 9 million soldiers, sailors and airmen died in the four years of conflict. That’s more than the population of New York City. Another estimated 6 million innocent people died as a result of the war, sometimes in attacks specifically targeting civilians.
"By the time they got to the First World War, the technology, the killing technology, had become really quite sophisticated for its time," said Yvonne McEwan of Edinburgh University's Center for the Study of Modern Conflict.
Modern warfare was revolutionized in those four years. The war began with fighters riding on horseback with rifles and ended with troops armed with machine guns and poisonous gas, on tanks, submarines and bombers.
Before the conflict began, empires ruled the world. The British Empire was at its peak. The Ottoman Empire controlled almost all the Middle East. Russia was run by a czar. The modern ideas of nationalism and owning a passport as we know it today simply did not exist.
By the end of the war, Europe’s power structures had completely changed. The Ottoman Empire broke up, and the Sykes-Picot treaty redrew the Middle East with consequences we deal with today. The Bolsheviks overthrew the czar, and the Soviet Union succeeded the Russian Empire.
The fighting essentially annihilated European economies, paving the way for the U.S. to become an economic powerhouse. Yet the U.S. was seen as a political teenager. The idea of turning to the Americans to play a decisive role in a global conflict was unheard of before then.
The war effort shattered traditions of daily life. For the first time in history, women en masse left the home and went to work. However, when women returned from the factories each day, many did not have husbands to return to. In Britain, for example, nearly 1.2 million women ages 25 to 34 were still not married by 1921 because so many young men died in battle.
From global leaders to people on the street, this week's centennial events serve as a reminder that much of the world is still touched, in some way, by World War I.
What did the countries fighting the Great War expect to happen?
Were they prepared for war on such a scale?
How did it change warfare, politics, economies and international relations?
We consulted a panel of experts for the Inside Story.