Sir Keir Starmer will attend Armistice Day commemorations in France on Monday - the first UK leader to do so since Winston Churchill in the Second World War.
Towns and cities across France will mark the 106th anniversary of the Armistice agreement in 1918 that brought fighting in the First World War to an end.
Sir Keir will attend the events at the personal invitation of President Emmanuel Macron and the pair will join British and French veterans and the public in paying tribute to the fallen.
It comes as the prime minister announces more than £10m to mark the 80th anniversaries of VE and VJ Day in the UK next year.
Sir Keir is expected to lay a wreath at Paris war memorials close to the Champ-Elysees, and also at the Tomb of the Unknown Soldier at the Arc de Triomphe, a national symbol in France for all those who died in the First World War.
The prime minister said: "I am honoured to be in Paris to stand united with President Macron in tribute to the fallen of the First World War who made the ultimate sacrifice for the freedom we enjoy today.
"These events are vital in ensuring the memory of millions of young soldiers, sailors, and aviators live on for generations to come."
Follow Sky News on WhatsApp
Keep up with all the latest news from the UK and around the world by following Sky News
Sir Keir and President Macron will also have talks ahead of the commemorations to discuss issues like the wars in Ukraine and Gaza.
Read more from Sky News:
Aftershocks of Trump win felt by European leaders
Scale of Russia's losses in Ukraine revealed
Please use Chrome browser for a more accessible video player
On Sunday, Remembrance events were held across the UK as the nation paid tribute to those who have served in the armed forces past and present.
King Charles, who is still receiving cancer treatment, paid his respects without the Queen, who did not attend events in central London due to a chest infection.
He appeared alongside his son Prince William and daughter-in-law, the Princess of Wales, who carried out two consecutive public engagements for the first time this year after her cancer treatment ended.