The Battle of the Somme is famous for its casualties.
On the first day almost 20,000 people were killed - four months later, more than a million soldiers had been killed or wounded on both sides of the fighting.
But the battle was also characterised by feats of bravery and valour, selfless fighting and missions of courage, with 49 Victoria Crosses being awarded to the Somme's soldiers.
The Victoria Cross was instituted by Queen Victoria in 1856. It is awarded for "most conspicuous bravery, or some daring or pre-eminent act of valour or self-sacrifice, or extreme devotion to duty in the presence of the enemy" to military and civilians.
The Victoria Cross may be awarded to all ranks of the services and has only been awarded 1,356 times.
On the 100-year anniversary of the battle, we bring you two of our favourite tales of bravery on the battlefield.
Lieutenant Tom Adlam
Tom Adlam, a bombing officer, stormed a German trench with less than 100 men. A brigade of troops had failed in the task seven times, but by throwing grenades as they walked down enemy lines, Lieutenant Adlam succeeded.
The next day he lead a team that took another trench. He was shot in the leg and then in his right-throwing arm, but simply swapped to throwing grenades left handed.
"He was very good at throwing," said Adlam's son, Clive Adlam.
Tom Adlam did not talk about the war, so Clive didn't know about his father's exploits until he was older, at which point he was astonished at his father's feat.
"I just felt like I could never ever have done anything like that myself and I remember he told me, he said he must have been mad at the time. I think he probably was," said Clive.
Captain Noel Godfrey Chavasse
Noel Godfrey Chavasse spent two days rescuing soldiers under heavy fire in No Man's Land as part of the Royal Army Medical Corps.
The announcement of his Victoria Cross in the London Gazette said: "He saved the lives of some 20 badly wounded men, besides the ordinary cases which passed through his hands. His courage and self-sacrifice were beyond praise."
Although Chavasse was injured himself, he dismissed the "two minute fragments of shell in my back" as "absolutely nothing", and continued to help soldiers.
Chavasse is one of only three people to ever be awarded a Victoria Cross twice.