A replica bomb is to be placed at a Rhayader beauty spot where it was tested during World War II after a campaign by pensioner Douglas Jones.
Mr Jones, 86, of Dutlas, near Knighton, said he was delighted the Elan Valley would finally be recognised for its role in The Dambusters raid. A showbusiness charity said it would pay for a replica bouncing bomb.
Last week, Emmerdale actor Richard Thorp, who plays Alan Turner in the ITV soap and appeared in The Dambusters film in the 1950s, joined Mr Jones’ campaign to recognise the Elan Valley and The Dambusters.
They dealt a blow to the German war machine in 1943 when they dropped bouncing bombs, designed by engineer Barnes Wallis.
Nineteen aircraft from the RAF’s 617 Squadron set out to destroy the Mohne, Eder and Sorpe dams in Germany’s industrial heartland, the Ruhr valley, but only 11 returned from the perilous low-level mission.
The attack was later to form the basis of the 1955 film The Dambusters, which starred Richard Todd, Michael Redgrave and a young Richard Thorp.
The Elan Valley, which has a series of reservoirs supplying water to Birmingham, was used to test explosives in 1942. As part of Wallis’ experiments, a large hole was blown in Nant-y-Gro dam.
Mr Jones, a World War II veteran said he had been campaigning for a replica bouncing bomb memorial for 10 years.
He added: “I spoke to the Heritage Foundation after some recent publicity about my campaign and they said they would pay for the replica bouncing bomb and a plaque.
“I couldn’t wish for better – I’m highly delighted. I’ve made dozens of phone calls and written dozens of letters during the campaign.”
The plans are to locate the memorial near the visitor centre in the Elan Valley.
The showbusiness charity, the Heritage Foundation, supports a variety of good causes.
Its chairman David Graham said: “I’ve spoken to Mr Jones and we’re happy to pay for this memorial, but it could be two years before it is put in place. We are currently fund-raising for a Bomber Command memorial in Green Park, London, so we’d like to sort this one out first.
“We’re happy to get behind this one. We think it’s important to recognise the sacrifice these people made and the determination and commitment they showed.”