The film Zulu is being screened on Bonfire Night for veterans whose Post-Traumatic Stress Disorder symptoms could be triggered by fireworks.
Rhondda Cynon Taf council and a group of veterans are showing the 1964 film starring Michael Caine which recounts the battle of Rorke's Drift in 1879.
More than 200 veterans have snapped up tickets to Tuesday's screening.
Paul Bromwell, a Falklands War veteran with PTSD, said the noise and smells of fireworks can trigger flashbacks.
He said: "Loud noise is what really affects veterans more than anything, especially when they live on their own.
"It's supporting each other more than anything, the guys that really need it. We're there for them."
The film, which also starred Ferndale-born actor Stanley Baker, is set in 1879 during the Zulu War in modern day South Africa.
Despite it showing graphic scenes of violence, the film was chosen by the veterans.
"I know it's one of these films where people will say - 'What the hell would they want to watch that for?' Mr Bromwell said.
"They just appreciate the film so much, and it's one of those films you can watch over and over again."
Stanley Baker's birthplace is not the only link to Wales in the film.
In the film, the regiment featured was made up of mostly Welsh soldiers and was based on The 24th Regiment of Foot from Brecon in Powys, less than 30 miles from where the screening is being held at the Park and Dare Theatre in Treorchy.
Maureen Webber, from the council, said: "While it is lovely to see so many people of all ages enjoying themselves on 5 November, the council is also very mindful of others who struggle to cope at this time of year.
"Fireworks going off, intense lights and sudden loud noises can cause people with PTSD to remember their own personal traumatic event in a split second."