Full coverage of the commemorations marking 100 years since the Battle of the Somme
The Battle of the Somme was fought between 1 July and 18 November 1916, with over a million British, French and German casualties
1 July 1916 remains the bloodiest day in British military history with 57,470 casualties, 19,240 of whom were killed
The centenary was marked by a national two minutes' silence at 07:28 on 1 July, the moment soldiers went over the top
Let us know about your commemorations using #Somme100
BBC Newsbeat
Jenny Leatherby's great-grandfather, Alfred Deadman, died during the Battle of the Somme when he was 28, the same age she is now.
She told Newsbeat what she would have liked to ask him.
History of World War One
The Somme - 1 July 1916 - 12.00pm
Around 100,000 British soldiers were deployed over the day. The British occupied some German trenches, but suffered around 50,000 casualties.
On the right wing of the Fourth Army forward trenches are captured. Across the rest of the line the battle was a disaster for the British, with the exception of the Ulster Division who were holding the Schwaben Redoubt, under intense German fire.
Today Programme
BBC Radio 4
In the opening hours of the battle, soldiers who were not far behind the front line were hearing sketchy reports of what was happening to their comrades.
James Heffer, 18, was one of them. He was with The Cambridgeshire Regiment a few miles north of the front line.
His son, the journalist Simon Heffer, reads James' diary from 1st July 1916, where he recorded: "We hear the British and French are advancing in the Somme."
UK Prime Minister David Cameron read a recollection of Corporal Jim Crow, from 110th Brigade, Royal Field Artillery.
It told of a brief, unofficial truce which took place in order to allow a wounded soldier to be rescued from No Man's Land.
History of World War One
Image source, Imperial War MuseumCap badge of the Sherwood Foresters (Nottinghamshire and Derbyshire Regiment).
The Robin Hood Rifles was made up of volunteers from Nottinghamshire and Derbyshire.
The soldiers were based on the northern part of the Somme at Gommecourt, and their job was to divert German forces away from the main attack. At the start of battle soldiers went over the top in a series of waves and came under intense fire from machine gun posts at Schwalben Nest on their left flank.
The commanding officer was killed and most of his men never made it across No Man's Land. By mid-morning the attacks were called off.
Out of the 800 men in the regiment who fought that day, 424 were killed or wounded.
BBC iWonder: Did one man's vision shape the way we bury our war dead?
Image source, Miranda MichelsBrothers, from left, Robert, Cecil and Tom Wilmot were all killed in World War One
Thousands who fought on the battlefield of the Somme died alongside their brothers, fathers, cousins and friends.
Kitty Wilmot lost three of her sons during World War One. Decades later, her granddaughter uncovered her tragic story.
The troops who've managed to reach the enemy positions are grimly trying to hold on. Many acts of valour take place as officers and NCOs try to rally their men. Actor Brian Cox tells the next update on the first day of battle.
1145 1st July, 1916
Image source, PA
Image source, AFP/GettyFrancois Hollande, David Cameron, Prince Charles and Prince William arriving at the event
BBC One
Dan Snow looks at the events of 1 July 1916, the bloodiest day in British military history.
Members of the Armed Forces and others have been reading first-hand accounts of those who were involved in the Battle of the Somme.
Actors Charles Dance and Joely Richardson introduced the readings.
After the first couple of readings The Morriston Orpheus Choir sang Ivor Novello's Keep the Home Fires Burning.
History of World War One
General Gough, commander of the Reserve Army, was charged with exploiting any breakthroughs in the German lines.
At 11.30am he issued his only order of morning and told the Cavalry divisions to hold off advancing until at least 2pm.
BBC iWonder: Has history misjudged the generals of World War One?, external
Some of our most striking images of World War One were created by the painters who visited the front lines. In this clip from The Arts Show, Steven Rainey explores the role of the war artist.
Commemorations, exhibitions and film screenings are being planned up and down the country to mark the centenary of the Somme.
Find an event near you, external
Image source, Imperial War MuseumScene from the Battle of the Somme film
Image source, AFP/GettyThe ceremony at Thiepval has begun, attended by 10,000 people.
It started shortly after the arrival of the Prince of Wales and Duchess of Cornwall - who lost three great uncles in World War One.
The UK and French national anthems were played to mark the start of the event.
Irish President Michael D Higgins shook hands with Francois Hollande and David Cameron as he arrived at Thiepval, then greeted members of the Royal Family.
Your Somme
What would you have been doing if you had been a young soldier in 1914? Try the Your Somme, externalprototype from BBC Connected Studios, and find out how many of your regiment from your local area would have survived.
UK Prime Minister David Cameron has shaken hands with French President Francois Hollande as he arrived at the Thiepval Memorial to the Missing of the Somme for the commemorative event, which is due to get under way shortly.
The Duke and Duchess of Cambridge, and Prince Harry, have arrived at Thiepval for this morning's ceremony.
A century after the Battle of the Somme, see battlefields and memorials from the air.