The only known footage of Wales' worst mining disaster has been donated to the National Screen and Sound Archive.
About three minutes of newsreel footage exist of the disaster
Newsreel film of the 1913 Senghennydd tragedy, in which 439 men died, has been handed to the Aberystwyth archive.
Oscar-winning editor Jim Clark originally found the three minutes of newsreel footage and used it in his 1964 documentary about Senghennydd.
The disaster happened on 14 October 1913 when explosions ripped through the pit at Senghennydd, near Caerphilly.
One underground blast at the pit was said to have been heard 11 miles away in Cardiff.
The brief surviving footage records the aftermath of the disaster at the Universal colliery.
The explosions and fires claimed the lives of 439 men
It contains images of people milling around the Senghennydd pithead in the wake of the disaster.
The film's opening title reads "A Terrible Calamity in Wales: Scenes of the Burning Pit".
A pall of smoke over the mine can be seen.
The 1913 footage was discovered in the Wardour Street area of London in the 1960s by editor Jim Clark, who later won an Oscar for best film editing for his work on The Killing Fields.
He bought the footage and used it as a preamble to his 1964 documentary Senghennydd: Portrait of A Mining Town.
He shot the documentary after his friend, former Cardiff businessman David Rees, told him of the disaster and suggested he filmed at Senghennydd.
'Enormity of disaster'
The entire documentary, containing the original 1913 footage, has now been given to the national archive.
Mr Clark, who had not seen the film for nearly 40 years prior to a screening at the Ffresh moving image festival in Aberystwyth last month, said he was pleased the footage is returning to Wales.
The Senghennydd tragedy was Wales' worst mining disaster
He added: "Before I filmed I had scarcely heard of Senghennydd and when I went there I didn't want to make a film about the disaster, but rather about the community."
Llinos Medi Jones, from the national archive, said the footage documented "one of the darkest chapters of 20th century Welsh history".
She added: "The newsreel footage in Clark's documentary captures the enormity of a disaster and its after-effects on the community.
"The Senghennydd [disaster] seems to us today to belong to a bygone age but is an important part of our history as a nation."
A copy of the documentary has also been loaned to Senghennydd Community Centre where a showing of the film is planned for 29 March.