With a terrible fascination, Hampshire joined the rest of Great Britain, and watched helplessly as an army of “our lads’’, stood with their backs against the sea on the beaches and sand dunes of Dunkirk in the early summer of 1940.

Anger quickly replaced helplessness and inspired owners of hundreds of small boats, mostly captained by fishermen, yachtsmen, and weekend sailors, to join the Royal Navy in a daring rescue mission, which successfully managed to transform defeat into one of the most heroic actions of the Second World War.

Many believe it was during this determined, rear-guard action by the Allies that the next great test of strength between good and evil was being plotted by Hitler.

Hitler decided the time was right to launch his greatest goal, “Operation Sealion’’, the invasion of Britain, but first he knew the RAF had to be destroyed.

Britain may have been battered and bruised after the shock of Dunkirk, but factories were working non-stop to re-arm, and Hitler made one huge blunder as he developed his invasion plans. Britain had one highly valuable, secret weapon in its war-chest, which would see the nation right through the years of painful conflict, and to eventual victory.

This was not man-made hardware of conflict, but the steely British character which refused to bend before evil.

Ranged against Britain were the Luftwaffe squadrons based in their newly-won airfields in France and the Low Countries. However, the enemy was unaware that the numbers of fighter aircraft being produced in UK factories far outstripped those emerging from German factories.

Another closely guarded secret was the desperate shortage of trained RAF pilots needed to fly the Spitfires and Hurricanes coming off the production lines. In the end airmen of 14 nations, many of them fugitives from the Nazi-overrun countries flew with the RAF that summer.

British military planners were faced with the uncomfortable question. “How long would the RAF’s ‘thin blue line’ be able to take the enormous pressures and strains, which undoubtedly lay ahead?’’ Opinions differ as to the precise dates of the start and finish of the Battle of Britain in 1940, although many historians considered it began on Wednesday, July 10, and ended on Thursday, October 10.

As the Spitfires and Hurricanes were scrambled to meet the attacking forces, the pilots, often not long out of their teenage years, performed twists and turns, leaving the awful beauty of vapour trails across the sky.

In those 114 days of the Battle of Britain the RAF losses amounted to 537 men and 1,017 aircraft.

Young men such as John Wadham, who began his working career as an apprentice with the former, Southampton furnishing company, Shepherd and Hedger. He joined the RAF Volunteer Reserve before war broke out and, as a 21-year-old sergeant pilot flying Hurricanes with 145 Squadron, Tangmere, was shot down by Messerschmitts on October 12.

If Britain’s death toll of young lives was the dire legacy of victory in the skies over the south coast, then the German losses of 2,662 men killed, and an estimated 1,882 planes shot down, were a heavy price to pay for defeat.

Air Chief Marshall Sir Hugh Dowding, in charge of Britain’s fighter command, later wrote: “The indomitable courage of the fighter pilots and the skill of their leaders brought us through the crisis, and the morale of the Germans eventually cracked because of the stupendous losses they sustained.’’ The “thin blue line’’ had held.