On Aug. 4, 1914, the Germans stormed into Belgium and formally began World War I, also known by the moniker the Great War. A hundred years later, Europe came together to remember its war torn past and the millions lost in the four-year conflict.

Representatives from 83 countries met in Liege, Belgium where the fighting began. Belgium's King Philippe, Queen Mathilde and outgoing Prime Minister Elio Di Rupo hosted France and Germany's presidents, Prince William and Kate Middleton and U.S. Secretary of the Army John M. McHugh, according to the Wall Street Journal.

"Peaceful Europe, unified Europe, democratic Europe. Peace is what our grandparents longed for," King Philippe said at the Allies' War Memorial of Cointe.

The day's events included candle-lit vigils, church services, wreath-layings, gun-salutes, military march-pasts and silences in Liege as well as in Mons and across the United Kingdom, according to the Guardian. British Prime Minister David Cameron called for a nationwide blackout from 10 p.m. to 11 p.m. to mark the exact hour Britain declared war on Germany.

"We were enemies more than once in the last century, and today we are friends and allies," Prince William said in his address. "We salute those who died to give us our freedom. We will remember them."

During the ceremony, French President Francois Hollande used the opportunity to highlight the modern day conflicts taking place in Gaza and Eastern Ukraine.

"Today neutrality is no longer an option," Hollande said in statement that deviated from his planned speech, according to the Wall Street Journal. "How can we stay neutral when a people, not far from Europe, is fighting for its rights and territorial integrity? How to stay neutral when a civilian aircraft can be shot out of the sky?"

He continued, "When in Gaza a murderous conflict has been going on for over a month... we cannot stay neutral, we have an obligation to act."

Europe descended quickly into total war after the assassination of Austrian Archduke Franz Ferdinand on June 28, 1914 during his visit to Sarajevo. The countries quickly divided into two opposing alliances. The United Kingdom, France and the Russian Empire (and the United States near the end of the war) made up the Allies, and Germany and Austria-Hungary made up the Central Powers. When Germany invaded neutral Belgium, Britain declared war on Germany and set off a domino effect for each European country (and later the world) to take sides.