Former enemies during World War I united for ceremonies surrounding the 100th anniversary of the start of the conflict, with Belgium, France, Germany and Britain standing together at an Allied memorial Monday to commemorate one of the great early battles.
In a spirit of reconciliation, Belgian King Philippe and Queen Mathilde welcomed German President Joachim Gauck under cloudy skies for the late-morning ceremony amid pomp and military honour.
Germany invaded neutral Belgium on August 4, 1914 as part of a planned attack on France. By nightfall, Britain had joined the war.
The war wasn't expected to last long.
Instead of weeks, the continent was plunged into unknown 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 will be ceremonies in Glasgow, Scotland, and a candlelit vigil at London's Westminster Abbey.
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, which 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.
By the end of autumn in 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 US joined the allies against the German and Austro-Hungarian empires in 1917 and provided a decisive impetus to break the deadlock before the November 11, 1918 armistice.