The calm that had prevailed in Newhaven during the first eight months of the war vanished abruptly in May 1940, following the success of the German blitzkrieg in Belgium and France. After Dunkirk, it was all too obvious that Britain's new front line was its shores - nowhere more so than in Sussex. 70 years after it was first planned and built to protect against a threat of invasion, which never materialised, Newhaven Fort was facing a very real danger of seaborne attack from a formidable enemy.

All along the coast, emergency measures were implemented to strengthen defences, often with elderly guns and equipment. More men were moved into the fort and large numbers of troops took up defensive positions around Seaford Bay.