Former enemies united Monday to commemorate the 100th anniversary of the start of World War I, with Belgium, France, Britain and Germany standing together in a spirit of reconciliation.
Belgian King Philippe and Queen Mathilde welcomed German President Joachim Gauck under cloudy skies for the late-morning ceremony at the Cointe allied memorial amid pomp and military honour. During the ceremonies, the former enemies sat united, listening and applauding each other's speeches.
Germany invaded neutral Belgium on Aug. 4, 1914, as part of a planned attack on France. By nightfall, Britain had joined the war.
"It opened Pandora's Box," said Gauck who acknowledged that it "is anything but self-evident to stand and talk to you on this day."
The war wasn't expected to last long. But instead of weeks, the continent was plunged into hardship and misery for more than four years.
Gauck will join British Princes William and Harry at the Saint Symphorien cemetery late Monday for a similar remembrance. In Britain, there was a ceremony in Glasgow, Scotland, and a late-evening candlelit vigil at London's Westminster Abbey.
The Great War, as it came to be known, is now often depicted as senseless slaughter without a big moral cause that claimed an estimated 14 million lives, including 5 million civilians as well as 9 million soldiers, sailors and airmen from 28 countries. At least 7 million troops were left permanently disabled.
British Prime Minister David Cameron sought to debunk that notion.
"Although there was an enormous amount of waste and loss of life, there was a cause that young men rallied to at the beginning of the war, which was the idea that Europe shouldn't be dominated by one power. That a country, a small country like Belgium, shouldn't be simply snuffed out," Cameron told the BBC.
On Sunday, an intense hug between Gauck and French President Francois Hollande during a remembrance ceremony in eastern France close to the German border sealed again the friendship between the two neighbours, who have become the cornerstones of the European Union.
Monday's ceremony in Liege was significant since the battle for the forts around the city meant the first delay for Germany's enveloping move through Belgium, the so-called Schlieffen Plan strategy to defeat France in a matter of weeks.
Liege held much longer than expected and allowed the allied forces to gather strength and keep Germany at bay within dozens of kilometres of Paris.
Gauck called the German plan "hapless" and deplored German actions against civilians and cities its forces passed through during the early weeks of the war.
By the end of autumn 1914, both sides dug in, and from the early battles, the war quickly changed into trench warfare on the Western Front, with hundreds of thousands of casualties in a barren landscape where poison gas often wafted through the air.
The battlefront scars would slowly and agonizingly rip across Europe, ravage whole communities and millions of families. It produced a moral wasteland in Germany that would become fertile ground for the rise of Nazism. Four empires would disappear.
The U.S. joined the allies against the German and Austro-Hungarian empires in 1917 and provided a decisive impetus to break the deadlock before the Nov. 11, 1918, armistice.