The BBC's Nick Higham has tweeted this image from St Symphorien cemetery, of an Anglo-German choir rehearsing for the ceremony later on Monday.

He tweets:, external "There will be recorded music too, from musicians of Berlin Phil and London Symph Orchs under Sir Simon Rattle."

The choir of Westminster Abbey are having their final rehearsals before tonight's service of remembrance.

Sara Smith
BBC News, Folkestone

says the archway unveiled in Folkestone marks the extraordinary role the town played in WW1. "It was known by many as the gateway to the trenches - the place where millions of men from across the British Empire left for war. As they did so they would have been able to hear the blasts, the booms and the firing going on just across the water," she says.

Image source, Getty Images

At the Tank Museum in Bovington, England, members of the Great War re-enactment society stand beneath a shower of a million poppy flowers, to remember the dead of WW1.

News from 1914
The world on the brink of war

Image source, Sheffield Archive and Local Studies

Sheffield Pals' Battalion

Lord Kitchener, in a bid to boost recruitment, promoted the 'Pals' scheme, where men from the same area signed up together.

One such battalion was formed at the University of Sheffield in September 1914, on the suggestion of two students there. Patriotic passion was at fever pitch, and within two days, 1,000 of the city's men had joined up.

Among those who lost their lives in WW1 were thousands of Sikh soldiers serving in the British Indian Army- some 83,000 Sikhs died in the First and Second World War combined and over 100,000 were wounded, says Col Robin Vickers.

Tim Willcox
BBC News, St Symphorien Military Cemetery, Belgium

says the Last Post is being played at St Symphorien Military Cemetery ahead of a ceremony of reconciliation there later. Choirs have also been practising through the afternoon at the spot, where an equal number of both German and British soldiers are buried.

Morpurgo, who wrote War Horse, a children's novel about a horse sold into the army and thrust into war in 1914, says he believes the "lights out" event is very fitting because it is "contemplative and quiet".

Image source, Getty Images

This picture of Chelsea pensioners taking part in a parade in London is one of many images in our gallery of this commemoration day.

Writer Michael Morpurgo says he grew up in London and was aware of the "ravages" of World War One but could not fully comprehend what the adults around him had experienced. "What settled upon me was the damage that war does, not just to buildings but to people and societies," he tells the BBC News Channel.

BBC World War One tweets: What #WW1 commemorations are happening near you? Share your images & stories with us using #Remember

Matthew Price, BBC News, Liege

"At the same time as people here were talking about peace and reconciliation and how Europe could never allow this to happen again, there was also a nod to the fact that conflict is never far away. French President Francois Hollande spoke of the other conflicts in the world at the moment. He said it wasn't enough for European leaders to come to events like this and talk about reconciliation and peace, Europe needs to be the guardian of peace and do more to try to bring about an end to those other conflicts."

News from 1914
The world on the brink of war

"It is impossible to give actual figures regarding the men who will need to leave Manchester and Salford in connection with the army and navy general mobilisation orders during the next few days… 20,000 is a fair estimate of the city's reserve contribution to the war." Manchester Evening News, 4 August 1914

Image source, Getty Images

Britain mobilises

Across the nation, the army mobilised for action. In August 1914, the British Army had only 700,000 available men. They were dwarfed by Germany's superior numbers of over 3.7 million soldiers.

Blood banks were developed during WW1, and war work turned some women's skin yellow. Read about these and other surprising facts about the war on BBC History.

Image source, Michael St Maur Sheil/Mary Evans

A century on, the battlefields of World War One are still littered with debris. This image shows probably the last battlefield burial site memorial left intact on the Western Front, with the soldier's equipment left on the grave, along with a plaque placed there by his father in 1919. The photograph is part of The Fields of Battle/Lands of Peace exhibition in London. More photographs can be seen on the BBC News website.

News from 1914
The world on the brink of war

Image source, Alan Vaughan

Australians take to the skies

At least half of the personnel in the Royal Air Force came from the overseas dominions of the British Empire. Australians were considered excellent pilots, and Australian squadrons were trained in England for service in France and Egypt.

The average life expectancy of a pilot at the front at that time was less than three weeks.

Image source, Other

Artist Jeremy Deller has created a series of films to mark the Lights Out events later on Monday. The work culminates in a film which will be available from 22:00 for just one hour. You can read more about the project on the BBC Arts website.

Michael Flood emails: My uncle, Joe Flood, fought in WW1. He belonged to the 2nd Battalion, The Prince of Wales Leinster Regiment, Royal Canadians. He was awarded the Military Medal for Bravery - 'For conspicuous gallantry and devotion to duty on 22 March 1918, while his country was suffering severe casualties.... Pte Flood showed the utmost disregard for danger, rallied other men and, by his action... setting throughout a fine example to all ranks'.

Joe thanked a prayer book for saving his life. It was in his breast pocket when a stray bullet hit him. He wasn't always lucky, though. His left arm was hit by an explosive bullet which shattered it. That brought an end to Joe's army career and he spent a year in a hospital in London before being given an honourable discharge in 1919. Joe and the many, many young men who died or were wounded in that terrible war should NEVER be forgotten.

Image source, EPA

German President Joachim Gauck spoke at the ceremony in Liege earlier, saying it was "unjustifiable" for Germany to have invaded Belgium. "We are grateful to have been able to live together with peace for so long in Europe," he said.

Sgt Jonathan St Paul, from Tunbridge Wells in southern England, is on deployment in Afghanistan. He told the BBC that the soldiers of World War One were "probably a lot tougher than us. You can only imagine the difference back then in trenches".

"Our generation, the PlayStation generation, has wifi and we can talk to our families on a daily basis. They probably had to wait weeks at a time to get their letters through."