It is now known that the German invasion plan, 'Operation Sea Lion' included a landing by the German 9th Army between Brighton and Beachy Head. Its 9th Division was to come ashore in Seaford Bay to capture Newhaven Port. However, the attack was anticipated and defence arrangements made, which included minefields, tank traps, and flame-throwers, in addition to various close defence preparations in and around the fort. The troops stationed in Newhaven Fort were in no doubt that they faced possible hand to hand combat with the invaders.

Real though the threat had been, the invasion never occurred. However, Newhaven Fort and surrounding area received much attention from the Luftwaffe. Bombing, machine gunning and incendiary attacks were almost daily occurrences. In 1942, a stick of bombs, which straddled Newhaven Fort, came near to hitting an explosive-laden blockship at the harbour mouth. A direct hit would have caused a huge explosion, putting an end to Newhaven Port’s activities, at least for some time.