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
Image source, Getty ImagesThe Battle of the Somme began by exploding huge mines underneath the German front line.
The largest was at La Boisselle and the crater - Lochnagar - survives today.
A ceremony is taking place there at 06:28 BST to mark the exact moment the mine went up, 100 years ago.
Image source, Getty ImagesOur live page coverage resumes this morning after overnight vigils took place at Westminster Abbey in London and in Scotland, Wales and Northern Ireland.
A two-minute silence is to be held at 07:28 BST to mark the start of the battle.
It will be followed by events in the UK and near the World War One battlefields in France.
We'll end tonight with images of the troops marching on the eve of the Battle of the Somme,100 years ago today.
From 06:30 BST tomorrow morning, we will bring you the stories of what happened to many of those who went over the top on 1 July 1916, as well as full coverage of the national commemorations happening throughout the day.
At Westminster Abbey this evening, students and teachers from 16 schools from across the country will be keeping vigil at the Tomb of the Unknown Warrior, each one held in the memory of individuals who played their part 100 years ago.
In all, 25 vigils will take place overnight, through to 07:30 BST on Friday - the moment the soldiers went over the top on the first day of the Battle of the Somme.
Those being commemorated at Westminster Abbey are:
The audio of the vigils will be uploaded overnight - follow @WW1_education, external and check the Centenary Battlefield Tours website, external to find out more about each of the people being remembered.
The Tomb of the Unknown Warrior in Westminster Abbey, which is open to the public overnight for the first time in more than 50 years
The Duchess of Cambridge and Princes William and Harry are attending a vigil being held at the Thiepval Memorial, near the battlefields of the Somme in northern France.
Speaking at the event, Prince William said the sacrifice of those who died there would never be forgotten.
Members of the British armed forces were among those who read excerpts of the diaries of troops who fought at the Somme.
Image source, Getty ImagesThiepval Memorial, France
The vigil in France is beginning.
Thiepval Memorial, the Memorial to the Missing of the Somme, is one of the largest memorials to Britain's war dead. The names of 72,000 British soldiers with no known grave are carved into the stone.
The memorial was designed by Sir Edwin Lutyens and was completed in 1932. It serves as an Anglo-French battle memorial and a small cemetery containing equal numbers of Commonwealth and French graves lies at the foot of the memorial.
The service at Westminster Abbey has concluded with the Queen laying a wreath at the Grave of the Unknown Warrior.
A vigil will be kept at the tomb, which holds an unidentified British soldier brought back from a European battlefield, all night.
What was going through soldiers' minds the night before they went over the top? Listen to those who were at the Somme on 30 June 1916 talk about their experiences.
Before the conflict of 1914-1918, wars were commemorated by celebrating the military leaders with ornate statues. The soldiers who had fought and died were buried in mass graves, often deemed unworthy of mention.
World War One would change this. Never before had so many soldiers of the British Empire marched off to fight - or died in such numbers. But one man was determined to find a way to mark the sacrifice of each individual who had given their life for the common cause. In doing so, he would bring about one of the most significant civic design innovations of our age.
BBC iWonder: Did one man's vision shape the way we bury our war dead?
Welsh First Minister Carwyn Jones has joined members of the Army, Royal Navy and the Royal Air Force for the vigil at Llandaff Cathedral in Cardiff.
First Minister Mr Jones said he was honoured to lead the event "to remember and reflect upon the sacrifices made by the one million men who were wounded or killed during the Battle of the Somme".
"Those who fought bravely for our futures should never be forgotten," he added.
"It is so important we all understand how the First World War changed our country forever, while we must also learn lessons to ensure such atrocities don't ever happen again."
The Queen, dressed in dark grey, and the Duke of Edinburgh are at the head of the congregation at Westminster Abbey, where an event to commemorate the Battle of the Somme is taking place.
Opening the service, the Dean of Westminster, the Very Reverend Dr John Hall, paid tribute to those who lost their lives in the bloody battle.
It was important to "continue to learn the lessons of history", and work to build lasting peace, he said.
In 1916, a Church of England clergyman serving at the Western Front in World War One spotted an inscription on an anonymous war grave which gave him an idea.
The Reverend David Railton caught sight of the grave in a back garden at Armentieres in France in 1916, with a rough cross upon which was pencilled the words "An Unknown British Soldier".
That moment of inspiration would blossom into a worldwide ceremony that is still being replicated in the 21st Century - the grave of an unknown warrior, symbolising those who made the ultimate sacrifice for their country.
An outdoor vigil is being held at the Somme Museum in County Down
Vigils are taking place tonight across the UK.
In Northern Ireland, a vigil opened to the public at 19:00 BST at the Somme Museum near Newtownards in County Down. It is being held outdoors.
BBC Northern Ireland is covering the event.
Westminster Abbey, London
On BBC Two, the service in Westminster is about to begin.
From 20:45 BST this evening, Westminster Abbey will open its doors to the public for an all-night vigil around the Grave of the Unknown Warrior. It will be the first time the Abbey has been open all night for a vigil since peace vigils were held for the Cuban Missile Crisis more than 50 years ago.
Quote MessageThe sacrifice of many thousands of lives in a battle which ultimately failed to achieve any serious breakthrough stands as a reminder of the suffering and loss involved in the First World War. As we imagine the feelings of those preparing for battle, the vigil will allow us to reflect on the cruel effects of warfare and to pray for lasting peace and justice in the world.
The Very Reverend Dr John Hall, Dean of Westminster
Tonight, we're remembering the ordinary men who faced extraordinary circumstances 100 years ago. Dan Snow tells their story.
Quote MessageWe decided to join up. We thought it would be a bit of a holiday. That's what we thought.
British soldier from WW1
For almost five months between July and November 1916, the Battle of the Somme was fought in the fields of northern France. It would change the landscape of World War One, redefine military tactics and move the Allies one step closer to victory.
The battle came with a cost. It inflicted heavy losses on both sides and was one of the bloodiest battles of the entire war.
Image source, Getty ImagesPozieres Memorial, France
For the British forces, the first day of the Battle of the Somme resulted in the heaviest losses ever suffered in British military history. By the time night fell on 1 July 2016, there were 57,470 casualties, 19,240 of whom died. The British had gained just three square miles of territory.
How did this bloodiest of days unfold? And what was it like for the 100,000 British soldiers who went over the top? Tomorrow, we look back in detail at the events that took place one hundred years ago.
One hundred years on from the eve of this battle, commemorations begin at Westminster Abbey, where Her Majesty the Queen and the Duke of Edinburgh lead the nation's remembrance at the Grave of the Unknown Warrior.
Huw Edwards is in Thiepval, France, and Kirsty Young is in Westminster Abbey, London, providing live coverage of vigil services held to commemorate the centenary.
Later this evening, The Duke and Duchess of Cambridge and Prince Harry will attend a vigil service at The Thiepval Memorial in France. The memorial bears the names of more than 72,000 men who died on the Somme and have no known grave.