Through the haze of a warm summer night came the heavy crackle of gunfire, the moan of aircraft and the shouts of wounded men as thousands of Allied troops scrambled from landing-craft on to the beaches of the French port of Dieppe. The Dieppe Raid had begun.
About a mile to the east of the town two women stood together on the balcony of a small hotel peering through the darkness towards the sea. They were tense and frightened as the noise of battle rumbled all around.
It was a scene familiar enough in wartime. But this was August 1961 and World War II had been over for 16 years. The women were convinced that what they had heard was a mysterious playback of a bitter battle fought 19 years earlier when the Allies made a daring raid to probe the strength of German defences.
Not surprisingly the incident has been a source of controversy ever since, with detractors believing the whole thing was a delusion and supporters convinced that it was an example of the human mind's mysterious ability to break through the barrier of time.
The women, sisters-in-law from England and on holiday in Dieppe with their children, shunned publicity for many years and only agreed to tell their story to researchers if they could remain anonymous. Since then they have always been referred to as simply Ann and Mary.
It had been a scorching day and the women had spent most of it on the beach with their children. Feeling healthily tired they went up to the room they shared - on the second floor room facing the sea — at about 10.30pm. At 4am Mary was shaken awake by a loud noise. She remembered: "At first I thought it was thunder but it got louder and seemed to be coming from the beach. There was shouting and distant rumbling. Then Ann woke too and asked what all the noise was. For a while we lay listening while the sound seemed to get louder."
Ann had served in the WRENS during the war in several battle zones and was in no doubt that they were hearing some sort of military attack. They went cautiously on to the balcony outside their window.
The town was asleep and nothing moved, not even a car, on the road leading to the beach. No one else seemed to have been disturbed by the unseen battle. Ann recalled to a research group: "We could hear troops but couldn't see anything or anyone. But the noise was real enough. We even ducked when we heard shells screech overhead."
At 4.30am the noise abruptly stopped but restarted 15 minutes later and became even more violent. But why had no one else run to their windows in response to the infernal din?
"As dawn broke, everything finally went quiet and the birds began to sing," Mary said. We began to wonder if it had all been a dream.
Later the women asked other guests if they had been disturbed in the night but no one had. Only Ann and Mary, it seemed, had by some trick of time, tuned into something that had happened nearly two decades earlier.
Some time later each wrote a separate account of what they had heard that night and sent the almost-identical reports to an investigator for the Society for Psychical Research.
An SPR team, fascinated by the incident, followed up the accounts and were able to work out a timetable of events which could then be compared with the schedule of the actual invasion.
Incredibly, it was found that the attacks, lulls and transport and aircraft movements corresponded almost exactly with the events of August 1942 when 6,000 British and Canadian troops landed on the Dieppe beaches planning to seize the town for a short period and destroy strategic buildings and equipment.
Virtually none of the objectives was achieved. It seemed the Germans had anticipated the raid and most of the landing force got no further than the beach. Over 3,000 Allied troops were either killed or captured. Over 100 RAF aircraft were shot down and a Royal Navy destroyer and 33 landing-craft lost.
The raid was regarded as a major tactical disaster although British Prime Minister Winston Churchill always maintained it had been necessary in order to test German defences prior to D-Day.
Was there any logical explanation for what the two women claimed to have heard? Possibilities included sounds from a cinema, artillery practice or even a gas explosion, but all were ruled out.
Interviewers reported that Ann and Mary "seemed well-balanced witnesses with no wish to colour their accounts."
Since then all manner of theories have been proposed. Did some sort of time machine click into reverse? Did the women somehow break into a fourth-dimension where long-forgotten sounds were preserved?
No one has ever come up with an explanation which bears serious scrutiny but investigators were agreed on one thing: Ann and Mary were telling the truth as they saw and heard it.
After all, what purpose could they have had in inventing anything as unlikely as a night-time battle of the ghosts?