Historians from the South are in France to unveil plans to map a 12 kilometre section of the Somme battlefield.
Today marks 97 years since the four-month offensive began in 1916.
It claimed more than 400,000 British casualties but only moved the line forward by a few miles.
Andy Robertshaw from Surrey and Steve Robertson from Kent are launching Project Beaumont-Hamel which plans to build up a comprehensive web database about one section of the battlefield.
It will draw on written sources but also involve archaeological digs.
The day before The Somme, more than 350 Sussex soldiers were killed in a diversionary attack meant to fool the enemy over the date of the real offensive.
The Battle of Boars Head also became known as The Day Sussex Died.
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Another cold and frosty night lies ahead, but the winter sunshine prevails for Friday.
Staying cold and frosty with plenty of winter sunshine.
Plenty of sunshine for some, but a little more cloud in the east and feeling cold