The blast hurled debris a mile into the air and left a crater, now known as Lochnagar crater, 200 feet across and 90 feet deep, which subsequently became the scene of fierce fighting for control of its rim.
At exactly the same moment this morning, Saturday 1 July 2006, 90 years later, a rocket flare soared into a clear morning crater, blew, an eerie echo of the sound thousands of 'Tommies' heard as they nervously waited to begin their perilous advance across a pulverised no-mans-land.
A loan piper advanced around the crater rim and joined the Somme pipe band next to a large wooden cross, scene of today's ceremony. Prayers, readings, and instrumental recitals lent dignity to the occasion, with a liturgy of inscriptions from a selection of graves up and down the Somme valley.
These inscriptions were slowly read out as organisations from Britain, France and Germany laid their wreaths. Before them stood nine small wooden crosses, each bearing a rusting British, French or German tin hat. The congregation of more than a thousand people stood silent as the colours and standards of the Royal British Legion, Army Cadets and other veterans' organisations were lowered for the 'Last Post'.
Silence
Then, two minutes silence, broken only by birdsong, the very birdsong that survivers of the first day's fighting remember as the week long artillery bombardment lifted and they waited for the whistle to go.
As the bugle notes drifted away, young children carrying baskets of poppy petals walked to the crater's edge and cast them to the summer breeze. It is almost certain that wherever they landed, ninety years ago a young man would have fallen.
One of those present, Colonel Hugh Boscawen, Director of Defence Studies for the Army, said:
"It is hard to believe, looking at this prosperous countryside, that so many people fought and died here. It is important, if we wish to honour these men, that we strive to work to avoid this sort of conflict and to gain the peace that these soldiers were prepared to die for.
"It is humbling to be able to visit these places today and to see the cemeteries like true "English gardens". We wish to pay our respects to those who fought here and also to make sure we learn the lessons we can draw from this momentous battle."
