The centenary of the Battle of Messines Ridge, where unionist and nationalist soldiers from Ireland fought side by side in the trenches, is to be marked by a joint UK-Irish ceremony.
The event will take place at the Island of Ireland Peace Park in Messines in Flanders, Belgium, on June 7 - the first day of the week-long battle, The UK's Northern Ireland secretary James Brokenshire announced.
Messines was the first occasion in World War One when soldiers from the 36th Ulster Division and 16th Irish Division saw action together.
Both had fought at the Somme in 1916, but at different stages of the battle.
The capture of the Messines salient in the summer of 1917, in part due to the detonation of a series of devastating underground mines below the German lines on the first day of the battle, marked a significant victory for the Allies.
Noting the "historic and symbolic" significance of the event, Mr Brokenshire said the UK and Irish governments were committed to working together to deliver a shared ceremony of commemoration.
"I am pleased to announce this shared UK-Ireland ceremony to mark the centenary of the Battle of Messines," he said.
"We have seen all too well how history can divide, but our ambitious goal throughout this decade of centenaries is to seek to use history to bring us together, and to build on the political progress that has been made throughout these islands.
"This shared ceremony is an opportunity to remember the service and sacrifice of those who fought at Messines Ridge, as well as to further strengthen the important relationship that exists between the United Kingdom and Ireland."
The ceremony will be a ticketed event. Members of the public wishing to express an interest in attending should go to: https://www.gov.uk/government/news/shared-uk-ireland-commemoration-announced-for-the-battle-of-messines-ridge
Minister for Foreign Affairs Charlie Flanagan said: "Almost a century ago, on the 7th June 1917, men and women from across the island of Ireland took part in the Battle of Messines in Flanders, Belgium.
"For the first time during World War One, soldiers from the 36th (Ulster) Division and the 16th (Irish) Division fought side by side.
"Those from the island of Ireland were brought together by diverse motivations but they shared a common purpose as soldiers and, caught up in the grim realities of war, no doubt a common desire: to survive and return home."
Mr Flanagan said a public ballot would be held in Ireland to allocate tickets.
More details are on: http://www.dfa.ie/commemorations/messines