European Union leaders meeting in Ypres to mark 100th anniversary of start of World War I

A wooden remembrance with a poppy is placed near names of the missing on the Menin Gate in Ypres, Belgium on Thursday, June 26, 2014. European Union heads of state will gather on Thursday for the first day of an EU summit in the city Ypres and will participate in a ceremony to commemorate the outbreak of World War I under the Menin Gate. (AP Photo/Virginia Mayo) (The Associated Press)

A Bench of Remembrance in front of the Menin Gate in Ypres, Belgium on Thursday, June 26, 2014. European Union heads of state will gather on Thursday for the first day of an EU summit in the city Ypres and will participate in a ceremony to commemorate the outbreak of World War I under the Menin Gate. The bench will be officially inaugurated at the summit. (AP Photo/Virginia Mayo) (The Associated Press)

Alan Siggee, from Swineshead, Linconshire, England, right, stands with his wife Audrey as he holds a photo of his father, World War I soldier Arthur Siggee, during a visit to the Menin Gate in Ypres, Belgium on Thursday, June 26, 2014. European Union heads of state will gather on Thursday for the first day of an EU summit in the city Ypres and will participate in a ceremony to commemorate the outbreak of World War I under the Menin Gate. (AP Photo/Virginia Mayo) (The Associated Press)

Where their countrymen once slaughtered each other with machine guns, artillery and poison gas, the leaders of Britain, Germany and the other member states of the European Union are gathering to solemnly mark the 100th anniversary of World War I and rededicate themselves to peace and working together.

EU President Herman Van Rompuy says "it will be a moving ceremony, because we are here, testifying to what Europe is: a project of peace, a project of solidarity, a project of cooperation."

At Thursday's proceedings in Ypres in western Flanders, where over a half-million soldiers died, EU leaders will attend the "Last Post," a bugle salute to the fallen performed each evening. They also will dedicate a memorial bench stamped with the word "peace" in the trade bloc's 24 official languages.