The Prime Minister will travel to Belgium and France to pay her respects to those who died in the First World War, as the centenary of the Armistice approaches.
Theresa May will visit two war cemeteries on Friday, to lay wreaths alongside French President Emmanuel Macron and Belgian Prime Minister Charles Michel.
She will start the day with a ceremony at the St Symphorien Military Cemetery in Mons.
There she will lay a wreath at the graves of John Parr, the first UK soldier to be killed in 1914, and the last, George Ellison, who was killed on the Western Front at 9.30am, before the Armistice came into effect at 11am.
Then she and Mr Michel will attend a reception where they will meet British and Belgian serving members of the Armed Forces.
Afterwards she will travel to France and meet Mr Macron in Albert, the town in the heart of the Somme region which suffered significant bombardment during the conflict.
The leaders will hold a private meeting and a working lunch before departing for a wreath-laying ceremony at the nearby Thiepval Memorial.
The memorial bears the names of more than 72,000 members of the Armed Forces who died in battle, and holds an annual commemoration for the Missing of the Somme.
A wreath combining poppies and le bleuet, the two national emblems of remembrance for Britain and France, will be made for the occasion.
Mrs May said the visit would be a chance to reflect on the time the countries spent fighting side by side in Europe, but also to look ahead to a “shared future, built on peace, prosperity and friendship”.
She added: “At St Symphorien I will have the honour of laying a wreath on behalf of a nation at the graves of both John Parr and George Ellison, the first and last UK soldiers to die during the war.
“That their graves lie opposite each other is a fitting and poignant symbol that brings home the eternal bond between them, and every member of the Armed Forces who gave their lives to protect what we hold so dear.
“We remember the heroes who lost their lives in the horror of the trenches.
“As the sun sets on one hundred years of remembrance, we will never forget their sacrifice.”
Returning to the UK on Saturday, Mrs May will attend the Royal British Legion Festival of Remembrance at the Royal Albert Hall.
On Remembrance Sunday she will lay a wreath at the Cenotaph and attend the national service to mark the Centenary of the Armistice at Westminster Abbey.