IN THE spring and early summer of 1944 a huge force of more than 1,500,000 military personnel spread across southern England, awaiting the greatest adventure in military history - the invasion of occupied Europe..

Allied forces, based in Devon, prepared for D-Day. But from 1943 another highly secret operation was under way in Kent.

Operation Hustle, officially codenamed Fortitude South, was the biggest confidence trick of all time and without it D-Day might not have succeeded. It saved many lives.

To fool Hitler, a skilled team worked hard to create the illusion of a large invasion force being massed in the South East.

Dummy tanks, lorries and aircraft built of inflatable rubber and canvas were placed in realistic looking "camps". Harbours were filled with fleets of mock landing craft. The deficiencies of these phoney vehicles was masked by camouflage netting. Roads and false storage depots were built.

To any German reconnaissance aircraft, it had to look very real. But a few master touches completed the sting.

Double agents sent false reports and manufactured radio traffic, which was routinely monitored by the Germans, helped create the illusion that the main invasion force was in Kent.

The Germans even swallowed the suggestion that the famous US military commander General Patton was in charge of the non-existent force.

Everything was done to the last detail. And Fortitude South worked.

The German army was convinced that Nord Pas de Calais, the narrowest point in the Channel, was the area of the planned invasion. Even as the Normandy landings started the Germans believed it was a trick to lure them away from the main event.

RAF bombers dropped tinfoil to send out confusing signals and dummy paratroopers were dropped. By the time the Germans realised they had been fooled, it was too late.

It was D-Day plus 1, a bridgehead was established in Normandy and Allied troops had started the journey to Berlin.