The Thiepval Memorial to the Missing is the largest Commonwealth War Graves Commission monument in the world, inscribed with the names of more than 72,000 soldiers whose bodies were never recovered or identified.
A daily service has been hosted there by the Royal British Legion to commemorate each day of the four-and-a-half month offensive, fought between 1 July and 18 November 1916.
The Rev Stephen Hancock, chaplain to the Royal British Legion Somme branch, said: "The trees and fields today mask the horror that once came here. I pray God that is never repeated and I pray God that the people who died are remembered."
Speaking before the service, the Rt Rev Nigel McCulloch, head of remembrance at the Royal British Legion, said those who fought had left an "enduring legacy" across the UK and Commonwealth.
He said the Royal British Legion had "led the nation in remembering the men whose sacrifice has come to symbolise the tragic scale and futility of modern industrialised warfare".
"The last day of the Somme is a moment to reflect on the collective sacrifice of all those who fought and fell in such tragic numbers between 1 July and 18 November 1916," he added.
For our part we remember the men of the Tyneside Irish, the Tyneside Scottish and the Northumberland Fusiliers whose lives were sacrificed on those cold wet bloody fields of France 100 years ago.