The 'Coastal Crust'

  • It is important to remember that the defences at Walberswick were only part of a much wider programme of fortifications that included other coastal and inland defences.

Wartime photo showing Britain's dfended coastline

Iconic wartime photo showing Britain's defended coastline. The coastal defences were only intended to slow down any invaders; once inland, German forces faced other obstacles. This photo shows a view of the east coast and was probably taken at Dunwich, a little to the south of Walberswick (Imperial War Museum)


  • Events in Europe in May 1940 necessitated radical changes in the nature of Britain's defence, as the coast became the front line against invasion.
  • On 27th May General Sir Edmund Ironside became Commander in Chief Home Forces and he immediately started the process of improving defences by the creation of what he termed the 'coastal crust'. 
  • This referred to an enormous building programme that was intended to fortify miles of potential landing beaches from the Wash to Dorset against the possibility of German landing. 
  • Work proceeded so rapidly that as early as 7th June Ironside was able to report that work on vulnerable beaches was well advanced.


  • A plan by General Headquarters for Home Defence of 15th June stated that coastal areas were to be 'regarded as an outpost zone to give warning of, and to delay and break up the initial attack.' 
  • Disembarkation was to be hampered by fixed defences, which were to be 'supplemented by other defence weapons such as lighter artillery, small arms, mines etc for their local protection.'


  • The coastal defences were, however, only one part of a wider defensive scheme. If enemy forces broke out from a beachhead they would have to negotiate a litany of ambushes, roadblocks and defended places. 
  • Some particularly vulnerable points were designed for defence by regular army troops, while other places manned by the Local Defence Volunteers (later the Home Guard). 
  • The intention here was to slow down German attempts to move away from a beachhead. Inland from the coast a series of linear 'stop lines' comprising anti-tank obstacles, roadblocks, pillboxes and trenches were also constructed. 
  • These lines were intended to prevent the kind of fast-moving armoured sweeps used to such effect by the Germans in France and the Low Countries and also provide a jumping off point for counter attacks.

  • The coastal crust was not, therefore, expected to halt any German landing in force; rather, it was expected to delay the enemy until mobile reserves inland could counter any landing. 
  • If the logic of the grand scheme is easy enough to comprehend, the reality for those charged with defending the beaches also had a grim simplicity to it. In one document the instrcutions are very clear: 'There can be no question of withdrawal on the part of any troops detailed to hold specific defences. Such troops will hold on to the end'.