The first line of defence was on the coastline, with all potential landing places obstructed with concrete blocks and/or poles to prevent glider landings. These covered all beaches from Fisherrow Sands in the west to Belhaven Bay in the east, and taking in Seton Sands, Gosford Bay, Aberlady Bay, GullaneBay, Broad Sands, Peffer Sands, Ravensheugh Sands and Tyne Sands. These defences were intended to prevent any enemy force from gaining a foothold from which to move inland. However, had these defences been overcome or bypassed the enemy would have found rapid advance prevented by an extensive series of roadblocks and other defences.
Roadblocks were built at all important road junctions, and many were given added protection in the form of flame traps. These were designed to spray petrol on tanks stopped at a road block. The petrol would then be ignited by one of the defenders, probably by throwing a Molotov Cocktail or other incendiary device. The resulting fire was not intended to destroy the tank, but would have starved its crew and engine of oxygen, thereby killing the crew and putting the tank out of action. There were 45 separate flame traps in East Lothian, of several different types, and had they been used it seems that they would have been highly effective in stopping an armoured column. This tactic would have been particularly effective whenever the ground sloped steeply away on either side of the road, thereby preventing tanks behind the lead vehicle from escaping the obstruction. Measures were also taken to crater roads using explosive charges in the path of an invading force, making the road impassable to road vehicles, and thereby often holding up an entire column.
One other flame weapon deserves particular mention. This
was apparently set up at the entrance to Dunbar harbour and would
have sprayed petrol onto the surface of the sea from perforated pipes. This would then have been ignited to, essentially, set the sea on fire (flamme fougasse). Thus, any hostile force attempting to enter Dunbar harbour would have been incinerated. The technique was also tried out on the south coast of England, and although never used at Dunbar or anywhere else would, no doubt, have proved most effective.
The county was also covered by a network of around 30
machine gun posts which would have proved invaluable in dealing with columns
of trucks carrying troops. Whilst the machine gun posts would eventually
have been overrun, they would have required time
for German troops to deal with; precious time which would have made it possible for mobile reserves to be called upon to deal with the invading force. Similarly seven pillboxes were constructed (at Levenhall, Goshen, two at the Wallyford Junction on top of the east coast railway line, Crookston School near Wallyford, Halfway House at Whitecraig and Prestonlinks Colliery) to provide stronger defensive positions and these too would have had a crucial delaying role.
More than 40 observation posts would have played an important role in tracking the movements of the invading force, thereby alerting the defences and providing useful intelligence on the strength of the attackers and their equipment.
There was, however, one location in East Lothian that
was considered especially vulnerable, so much so that an extensive network
of defences was built, resulting in its classification as a Defended Area.
The bridges crossing the Dunglass Burn, just inside the boundary with
Berwickshire, carried the Al and the east coast railway line, crucial
arterial routes which would have been a tempting target for a small commando-style
raid. Rumour had it that there was an off-shore trench in which U-boats
would lie in wait to
pounce on unsuspecting ships and this would also provide the perfect position for a U-boat to wait before surfacing to send commandos ashore at night. Consequently sizeable resources were devoted to the defence of the bridges.
At the mouth of Bilsdean Burn and on top of the cliff on the left bank of the creek wire entanglements were erected. An extensive minefield was laid at the mouth of Dunglass Burn stretching up to the cliffs on either side. Further wire entanglements were placed on the banks of Dunglass Burn, on the upstream side of the bridges, as well as at Dunglass Mains Farm. On the bridges themselves road (and rail) blocks were erected, with that on the road bridge covered by a rifle pit dug into the road surface. A pillbox was also constructed on Dunglass Viaduct to strengthen the defence, and the pillbox and rifle pit would have provided mutually supporting fire.
It can be seen that the Dunglass Burn bridges were defended by extensive inter-linked works, manned by troops housed in a camp just upstream. Although heavily defended, these bridges were just one part of the anti-invasion defences in East Lothian which, although never put to the test, would surely have proved worthy of the effort invested in them.