It will take another five centuries to clear the Somme battlefields before the area is safe, bomb disposal experts warned on Thursday after collecting 25 tons of munitions this year alone.
Details of the potentially lethal "Iron Harvest" came as members of the Royal family including Princes Charles and Harry were due to arrive in northern France to commemorate the 100th anniversary of the bloody battle.
Michel Colling, head of the Amiens bomb disposal unit that handles the Somme, said: "Since the start of the year we've been called out 300 times to dispose of 25 tons of bombs.
"As soon as you start turning the earth up, you find them. At this rate, we have another 500 years to clear the area, so the work is far from over," he told the Telegraph.
It came as French farmers continued to hand out earth-caked shell cases, fuses, and even discarded guns to visitors from the UK.
Mr Colling said: ‘We find all kinds of devices. The biggest to date was an eight hundred kilo, 15in British bomb at Thiepval, and the smallest are the grenades ...
The first day of the Somme campaign on July 1st 1916, was the deadliest day in British military history, with almost 20,000 soldiers left dead ...
After the Treaty of Versailles Allied Supreme Commander General Ferdinand Foch said "This is not a peace. It is an armistice for twenty years".
World War II started twenty years later.