One of Britain's few remaining World War I veterans is travelling to France to attend a ceremony to mark the 90th anniversary of the Battle of the Somme.
Mr Allingham met Tony Blair in Downing Street on Veterans' Day
Henry Allingham, 110, the UK's oldest man, served as an aircraft engineer at the Somme and will attend a service at the Thiepval British memorial.
Saturday's commemorations will also be attended by the Prince of Wales and the Duchess of Cornwall.
Mr Allingham is setting out on Thursday from his care home near Brighton.
He moved to St Dunstan's recently from Eastbourne, East Sussex, where he had lived for 40 years.
On Friday he will visit the British Air Services Memorial at St Omer, which he opened in 2004 to honour his fallen comrades.
"We are coming to the very end of a very special generation of men and women," said Dennis Goodwin, chairman of the WWI Veterans' Association and a close friend of Mr Allingham.
"Henry does it because he says he owes it to the men. As long as he can go forth, their valour and sacrifice cannot be forgotten," he said.
The British losses on the first day of the Battle of the Somme on 1 July 1916 were the Army's worst ever for a single day.
It suffered 60,000 casualties, of whom almost 20,000 were killed.
On Tuesday, Mr Allingham was at No 10 Downing Street for a reception for military veterans and met Prime Minister Tony Blair.
On his 110th birthday earlier this month, Chancellor of the Exchequer Gordon Brown visited him in Eastbourne to hand over a message from the Queen.