The earliest aerial bombs were tested at the secret wilderness of Orford Ness during the First World War. The long spit of land was also an early test site for British radar, which played a crucial role in winning the Battle of Britain in the Second World War.
During the Cold War, the Atomic Weapons Research Establishment (AWRE) had an outstation on the site, where it stressed and strained nuclear warheads to ensure that they would still detonate after the rigours of their brief missile flight to the Soviet Union.
Orford Ness will be opened to the public after being strictly off-limits for most of this century. But the trust will have to spend several years and about pounds 1m tidying up the mess left by the military.
'The place is steeped in military history,' said Gordon Kinsey, a local author who has written a book on the ness. 'There are all sorts of myths about it and it's wonderful that people will be allowed to go there and find out what went on.'
The trust bought the 1,550 acres of land from the Ministry of Defence for just under pounds 300,000 in order to preserve one of the few large pieces of wilderness remaining in southern England. It is a sanctuary for thousands of gulls, waders and wildfowl and a rare landform - 'the most important shingle spit cuspate foreland complex in Britain', according to English Nature.
The total cost of the acquisition will be pounds 3.5m, which will cover the restoration costs and the setting up of an endowment fund to conserve the ness. The Countryside Commission is providing most of the funding, pounds 2.3m, with additional cash from local councils.
There are more than 100 military buildings in various states of ruin. Many will be demolished. A few date back to 1915 when the experimental flying section of the Royal Flying Corps began military occupation of the ness. The most spectacular buildings are two huge concrete pavilions built by the AWRE, which left the site in 1971. Nuclear warheads were tested in the pit in the centre of the structure.
The pillars supporting the concrete roof were designed to collapse if the conventional explosive in a warhead should accidentally detonate (this conventional explosive is used to trigger the nuclear chain reaction when the weapon is fired in anger). The heavy roof would then fall, sealing off the pit. The trust will not demolish these landmarks because of the high cost and their part in the site's history.
Another AWRE building contains a large, crumbling centrifuge where warhead components once spun at speed, simulating the huge forces it would experience during missile flight. Now it is full of flowering weeds.
Decades of military activities have damaged the covering of specialised plants which can survive on the ness. Excursions across the shingle by four-wheel drive enthusiasts have done further harm.
A large part of the ness belongs to the Foreign Office, which operates a transmitting station for the BBC World Service.
One of the National Trust's first priorities will be to restrict people walking or driving on to the spit at Aldeburgh, where it joins the mainland. This could make it unpopular because hundreds of anglers walk out along the spit to fish. There is already a barrier at the landward end but it has been broken.
The trust hopes that by 1995 people will be able to visit using a ferry to cross the short stretch of water from Orford. The trust now owns the northern end of the ness, while the southern half, a national nature reserve, belongs to English Nature, the Government's conservation arm.