Machine guns salvaged from the wrecked landing craft were set up in the beach defences.
The beach defences seen at the foot of the Rock in the initial shot were also added solely for the film, to an otherwise non-military area.
Once clear of the beach defences they found themselves in a relatively quite sector.
The approach was from the town quay, across the harbour, through the beach defences onto the Cape and into the U-boat repair docks.
It was hoped that preliminary naval and air bombardment would soften up the beach defences and destroy coastal strongpoints.
Tank obstacles, land mines and beach defences were put in place around the Fort.
Its objectives were to reconnoitre and damage the beach defences, take prisoners and destroy a searchlight battery.
Back in England, he took on responsibility for the beach defences in Devon and Cornwall, where many of his pillboxes still stand today.
Another large contribution was the 15,000 miles of tube, used for the construction of beach defences, termed Admiralty scaffolding.
It was then that the British conducted a review of the beach defences.