One of the major focuses of Belgium’s commemorations to mark the Centenary of the outbreak of World War I will be the Fort de Loncin.

The fortress, one of 12 that formed a defensive semi-circle around the city of Liege, was the scene of terrible loss of life on 15 August 1914, when a shell from a German Big Bertha artillery piece exploded inside its magazine.

Loncin had been under siege for several days, had been hit by thousands of artillery shells and the majority of its garrison had assembled in the main chamber, positioned just above the ammunition store.

They had gathered here partly because the air in much of the rest of the fort had become unbreathable and partly because they were expecting an imminent German infantry attack and were in readiness to rush outside to take up defensive positions.

Around 300 of them were killed in the blast and around 200 of those still lie buried under wreckage and rubble at the fort to this day.

The fortress is open to the public and is a sombre, moving place. Some parts of it, including soldiers’ accommodation, bakery and shower rooms remain much as they would have been in 1914. Elsewhere the devastation is dreadful, with huge lumps of smashed concrete and gun turrets that were ripped from their moorings by the force of the explosion.

A small museum tells the story of the building of the fort – fatally, in non-reinforced concrete – in the late 19th-century. It also has displays focused on the garrison of artillery and infantrymen and how the process of identifying casualties continues to this day.

Most poignant of all is a small selection of personal items recovered from the wreckage over the years. Some of these, such as a gold wedding ring and a Browning pistol, have proved crucial in the identification of a missing man.

Every year on August 15 at 5.25pm – the time the fort was destroyed – its last surviving gun fires a salute and a flame is lit at the monument to those who remain buried on the site.

To find out more about visiting the fort, click here.