General Background
In April 1940, Germany invaded Denmark and Norway. Following the withdrawal of the British Expeditionary Force from continental Europe with the evacuation from Dunkirk and the fall of France at the end of May 1940, Britain was effectively surrounded by occupied territory. The Nazi-Soviet Pact which partitioned Poland meant that Germany could concentrate forces in the west. The threat of an invasion of the British Isles was high.
We now know that the German plan for invasion (Operation Seelowe – “Sea Lion”) involved the short sea crossing at the eastern end of the Channel. But at the time, it was believed that the threat of invasion by air or sea could materialise almost anywhere. Certainly the possibility of forces crossing from Norway and Denmark could not be discounted; and eastern Scotland was fortified against this eventuality.
Defences took two main forms. Around the shore the so-called “Coastal Crust” was formed. Using fixed defences such as pill-boxes, trench-lines, concertina wire, minefields and anti-tank blocks, the areas of the coast judged vulnerable to invasion were hardened. Areas where glider-borne forces could land were also interdicted using networks of large upright poles. These fixed defences tell only part of the story. Until recently it was not generally known that the British authorities were also committed to using chemical weapons to defend against invasion. Airfields near coastal areas held stores of mustard gas and air units based there were secretly tasked with delivering the gas in aerosol form over the beaches if the invasion threat materialised. One of the airfields and units so charged was No 614 Squadron at RAF Macmerry
Inland, lines of fixed defences, usually arranged along natural obstacles such as rivers or canals, were set up as “Stop Lines” to hold and slow invading forces once ashore. East Lothian had no designated Stop Lines. However, McKryton has set up a series of caches in Fife to mark elements of the Fife Stop Line which gives an excellent picture of how defences would be managed to slow and destroy invading forces. A Bookmark list of these caches is here.
There are two related websites which deal with the Second WorldWar in East Lothian. One is run by the East Lothian Museums Service. The other relates to a two-volume book “East Lothian at War” (Volume One is now out of print.)
This article in Wikipaedia gives a helpful summary of British anti-invasion defences.
Aberlady Anti-Tank Blocks
Park at the small car park at N56 00.856 W002 50.987. This is also the parking spot for Aberlady Bay and Get to the Point! and the caches can be combined in a circular walk.
Anti tank blocks were produced to standard patterns (cubes 5 feet or 3.5 feet to a side) in vast numbers round the coast of the UK. They were mostly cast on site using timber shuttering. There are sometimes graffiti from the builders traced in the concrete before it hardened. The blocks were usually sited on concrete rafts. They could be used in a variety of combinations. A line of single blocks is still in place around Links Wood Road Block and there is a line of double blocks along the Tyne estuary close to the Sweet Course of the Tyne Diner series.
The double line of blocks around the shoreline and out into what is now Aberlady Nature Reserve is well seen in this contemporary picture:
Blocks were used in combination with other defences to channel lines of advance and to slow the progress of vehicles. Tanks and other tracked vehicles might be able to climb lines of blocks but in doing so would expose their lightly (in some case un-) armoured undersides.
Most of the blocks around the coast have now been removed. Some have been used in sea defences and others have been dumped out of the way of the beaches they once covered. The serried ranks, 4 deep, on this slope in Aberlady Bay are interesting. This may be a dump of blocks taken from the beach; but the fact that the blocks here are carefully arranged in ranks down the slope and the rafts are well sunk in the bank (only one block has fallen) leads me to think this is an original defensive position. Either way, it gives a good sense of how strong a barrier a multiple line of blocks could be.