The Berkshire village where Allied troops trained for D-Day in 1944

A popular hiking trail once trained Allied troops to win the war.

The Merville Gun Battery in Normandy posed a serious threat to the success of D-Day.

And so the Allies organised a huge military training exercise at Inkpen in May 1944 to prepare for one of their biggest missions of the Second World War.

In Britain, the commanding officer of the 9th Battalion of the Parachute Regiment, lieutenant colonel Terence BH Otway, ordered his troops to construct a full-scale replica of the Merville Battery and the route from the Drop Zone.

Colonel Otway later recalled: "The brigade major, Bill Collingwood and I, flew over the [Berkshire] area, and we found this place near Newbury called Walbury Hill. It’s a long ridge, about 800 feet high, very narrow at the top, so it was ideal for live ammunition.

"Then I went to see the owner, who was a farmer. He was very good about it, because we could have slapped a compulsory order on him. One landowner was a bit difficult. He happened to be a retired lieutenant colonel from the First World War, but I took him in and gave him a gin."

The Civil Service told Colonel Otway he required permission for the exercise. "To hell with that. I’m doing it, and I’m doing it tomorrow," was his response.

On the night of May 8, the battalion camped in a nearby field at West Woodhay. The distance between the camp and the drop site matched that between the real drop site and battery.

"At one corner of the field, a large marquee had been erected and when we had all settled in, it was here that the CO told us why we had come to this area," said private Ron Tucker of 'C' Company.

"We learned all the details, except where in France or on which day we would go to destroy the guns, but it was the middle of May, and we expected it would be only a matter of days."

The morning after their arrival, paratroopers helped the Royal Engineers to create the mock battery using tubular scaffolding covered with canvas, and accurately re-produced minefields, tank traps, trenches, wire, plus hedges, trees and tracks. Training then commenced with both day and night attacks.

Private Tucker added: "At first, we simply walked into the attack to make sure of our movements, then we made it as close to the real thing as we could without firing a shot.

"By this time, everyone knew just where he was supposed to go, where the enemy troops would be and which ones each of us had to kill. The only things we did not know were their names and the colour of their hair."

At midnight on June 6, 700 paratroopers descended upon their target with strict orders to destroy the heavy gun placements by dawn to allow the seaborne invasion to begin. The troops were widely scattered, meaning only 150 men assembled for the assault.

Armed with one heavy machine and knowing Lancaster bombers had not weakened the target as planned, their mission proceeded.

The operation saved many Allied troops who landed on Sword Beach to launch the liberation of Europe. Colonel Otway lost almost half his men. He received a Distinguished Service Order for the mission's success.

The Merville Gun Battery was one of many coastal defence fortifications dotted along the Nazis' Atlantic Wall, built to defend continental Europe against an Allied invasion.

The site included a command bunker, an accommodation block and an ammunition store. It was defended by a 20mm anti-aircraft gun and 15 machine gun positions, surrounded by two barbed wire obstacles, a minefield and an anti-tank ditch. German field marshal Erwin Rommel inspected the early defences in March 1944, which were completed two months later.

Various other units took part in the mission, including one section of the 4th Airlanding Anti-Tank Battery Royal Artillery, which was responsible for dealing with the steel doors of the casemates (small rooms in a fortress).

Also, the sappers' duty was to destroy the guns, and the medical teams of the 224 Field (Parachute) Ambulance were to treat and dress wounds, but could carry out major operations if required.

(Based on research contributed by local historian, John Leete.)