A row of 22 anti-tank blocks stride across the marsh at the south end of Shingle Street where it joins Bawdsey Beach. Today it seems a strange spot for such defences, but once it blocked an exit off the beach and was part of a bigger set of obstacles and a battery that have long since gone. Between Felixstowe and The Wash around 28,000 such redoubts were constructed in 1940 in the face of the expected invasion by Nazi Germany (Operation Sealion). Around 6,000 survive – many are hidden, others have now become part of the landscape.