Survivors and families of those killed in the Claudy bombings 50 years ago will gather in the quiet Co Londonderry village later to mark the anniversary.
A cross-community service with readings and hymns will take place at the memorial in the village.
Nine people, Catholics and Protestants, were killed and 30 injured when three car bombs exploded in the village on July 31 1972.
The victims included nine-year-old Kathryn Eakin, who had been cleaning the windows of her family’s grocery business, Patrick Connolly, 15, and 16-year-old William Temple.
The adults killed were Artie Hone, 38, Joseph McCluskey, 39, Elizabeth McElhinney, 59, James McClelland, 65, Rose McLaughlin, 52, and David Miller, 60.
The attack was blamed on the Provisional IRA, although the group has never claimed it.
No one has ever been convicted for the attack.
Several of the bereaved families are continuing legal action against the Catholic Church after a Police Ombudsman report in 2010 found that a Catholic priest, the late Father James Chesney, was a suspect.
The report said police, the state and the Catholic Church covered up his suspected role in the bombing.
Victims’ Group South East Fermanagh Foundation (SEFF) has been supporting the families over the last 12 months in developing a range of projects and events designed to mark the anniversary.
Director of services Kenny Donaldson said: “We have enjoyed a relationship with the Claudy families for a number of years but over the last 12 months we have worked collaboratively with all nine bereaved families, injured persons, the churches, schools and a range of others in developing a series of events designed to mark a milestone anniversary of 50 years.”
He added: “The bombings of Claudy were an attack upon the full community of the area and so it proved with nine innocents dying, young and older, male and female, Protestant and Roman Catholic – these neighbours died together and Claudy as a small village was forever changed.
“The bereaved families have shared their lived experiences over recent months with an appointed project facilitator culminating in the production of a publication which will be launched on the day of the anniversary.
“The schools have also developed a digital-based project, working together in partnership looking at the past within Claudy, the present and what they desire for the future.
“There will also be a community-based public service held on Sunday at the Claudy Memorial and within the main car park, commencing at 3pm.”
SDLP East Derry MLA Cara Hunter has said the impact of the Claudy bombing still has a profound impact on the area after 50 years.
She said: “My thoughts are with the families of the victims and all those affected ahead of the 50th anniversary of the Claudy bombing.
“The events of that day have cast a dark shadow over this village that still remains to this day.
“As a result of this bombing multiple families and a community was torn apart and for many the pain is still as real today as it was when this disgraceful act was carried out.”