Former enemies Belgium, France, Britain and Germany unite during ceremonies marking start WWI

Resident Marilyn Lahaeu holds up a photo of World War I soldier Pvt. George Lawrence Price, who was killed in the Belgian village of Ville-sur-Haine, in 1918, near her home in Ville-sur-Haine, Belgium, Sunday, Aug. 3, 2014. An international ceremony will take place on Monday, Aug. 4, 2014 at St. Symphorien Cemetery near Mons, Belgium to commemorate 100 years since the start of WWI. Pvt. George Lawrence Price was killed in action on Nov. 11, 1918 just two minutes before the Armistice. He is known as the last Canadian soldier to die on the Western Front in the First World War. (AP Photo/Virginia Mayo) (The Associated Press)

Resident Marilyn Lahaeu holds up a photo of World War I soldier Pvt. George Lawrence Price, who was killed in the Belgian village of Ville-sur-Haine, in 1918, near her home in Ville-sur-Haine, Belgium, Sunday, Aug. 3, 2014. An international ceremony will take place on Monday, Aug. 4, 2014 at St. Symphorien Cemetery near Mons, Belgium to commemorate 100 years since the start of WWI. Pvt. George Lawrence Price was killed in action on Nov. 11, 1918 just two minutes before the Armistice. He is known as the last Canadian soldier to die on the Western Front in the First World War. (AP Photo/Virginia Mayo) (The Associated Press)

Heads of state and foreign dignitaries, including German President Joachim Gauck and his French counterpart Francois Hollande, are gathering at an Allied memorial to commemorate the start of World War I.

In a spirit of reconciliation among former enemies, Belgian King Philippe and Queen Mathilde welcomed Gauck under cloudy skies for the late-morning ceremony amid pomp and military honor.

Germany invaded neutral Belgium on Aug. 4, 1914 as part of a planned attack on France. By nightfall, Britain had joined the war.

The war was not expected to last long. Instead, over four years, the continent was plunged into unknown hardship and misery.

Further remembrance events are planned in Belgium and Britain throughout the day.