On 1 July 1916 the piercing sound of whistles filled the air as men climbed from their trenches to advance. And so began 141 days of the bloodiest battle of World War One.
Those soldiers were surrounded by comrades and driven forward by determination, duty and fear. The prospects of reaching the enemy trenches were grim as whole waves of men fell to the storm of oncoming fire which spread across the battlefield. By nightfall 21,000 would lay dead and 35,000 more would have been wounded in the first day on the Somme.
Many had answered the call to join Lord Kitchener's new army to fight alongside neighbours and colleagues. Their anxiety that the war would end by Christmas before they saw action would prove sadly misplaced. Barnsley alone raised two battalions, proudly named the 1st and 2nd Barnsley Pals which joined the York and Lancaster Regiment. A story of patriotism and adventure retold across the country and Empire as men from all backgrounds joined together; trained together; went to war together; and ultimately, many of them died together that day.
This week I travelled to Northern France to pay my respects to those soldiers. Men who were prepared to face danger to secure freedom for people they would never meet, and never know.
I stood in the trenches they had defended. I imagined the terror they must have experienced and walked the ground over which they had fought. Open rolling countryside that has changed little over the past century. Then I knelt in front of their graves. It felt like they were a long way from home.
Their memory can bring us closer to understanding ourselves. In many ways the First World War marked the true beginning of the 20th Century, setting events in motion that would shape generations to come and the lives we lead today. We live in peace and enjoy freedom because of what they and others did for us. That is a legacy which will endure for all time. Teaching us in our own lives to always strive to do more to help others and build a better world through our actions.
The scale of the battle is difficult to comprehend. Beforehand, the sound could be heard from England as a week-long barrage of guns fired more shells at the German line than had been fired in the first year of war. Soldiers began to enter No Man's Land shortly before 7.30am to lay in whatever shelter was around in the open. The world then seemed to shake as the final mines detonated under the German lines, and in the noise and light of that moment the Pals lay ready.
A brief silence fell before the advance started. As the heat of the summer day was met with the dust and noise of slaughter, fierce battles raged for control of the German trenches. In parts of the front later that night, local truces between soldiers allowed the wounded to be removed.
The events of the Somme extended beyond the trenches to touch the lives of nearly every community across the UK and beyond. In the weeks and months that followed blinds would be drawn across working-class streets all over the country as the dead were mourned. Local newspapers published rows of photographs of young men as around half of those who joined the attack became casualties on that one day. For every yard of the sixteen-mile front there were two British casualties.
Reflecting back on that one day of senseless slaughter helps us to look forward. This weekend people around the country will pause and think about the First World War. It is a measure of our common decency that despite WW1 being a war of history, not memory, we commemorate it. Every part of our country has its own story. Of the 16,000 towns and villages across Britain in 1914, only 40 thankful parishes would see the return by 1918 of all who had left for the conflict. The horror of that appalling loss will live on for future generations as we learn the lessons of our past.
The First World War did not only change our society forever, it shaped our continent. Conflict would return once again before the tensions of war in time gave way to the partnerships of peace. Today it is comforting to know that what were once fields of war are now fields of peace.
A hundred summers on from the Battle of the Somme we should remember that sacrifice and reflect on how it changed our society then and shaped Britain today. In doing so we recognise it is a measure of our common humanity that we must ensure it never happens again.
Dan Jarvis is the Labour MP for Barnsley Central