In the Dutch coastal town of IJmuiden, the Germans built two gargantuan bunkers for their Schnellboots (called E-Boats by the Allies). Only one of them survived the war. That bunker is 247 meters long, 74 meters wide, 18 meters tall, they do not get much bigger than this!
Still taken from a United States Army film, shot during the bombing of the German bunker Schnellbootbunker BY (SBB2), February 1945.
After the German invasion of the Netherlands on 10 May 1940, the Dutch Royal family left the country from IJmuiden in the late evening of 12 May. Some were on board the British destroyer HMS Codrington, while Queen Wilhelmina left on board HMS Hereward. The quays at IJmuiden were crowded at that time with people desperate to be transported across the channel, sometimes at great expense. During the German occupation, the canal was out of operation and the Germans destroyed most of IJmuiden to create what they called Festung IJmuiden (Fortress IJmuiden), a heavily defended area in which the entire civilian population had been removed.
IJmuiden became the site of two separate fortified pens constructed by the German navy (Kriegsmarine) to house their schnellboote (fast torpedo boats, known to the Allies as E-boats) and Biber midget submarines. The older structure, codename Schnellbootbunker AY (SBB1), was protected by a 10-foot (3.0 m) thick concrete roof. The newer one, codename Schnellbootbunker BY (SBB2), had 10–12 feet (3.0–3.7 m) of concrete, with a further 2–4-foot (0.6–1.2 m) layer separated by an air–gap.
The E-boats laid up in the shelters during the day, safe from air–attack, and put to sea under cover of night to attack Allied shipping. The pens were priority targets after D-day as the torpedo boats they protected were a considerable threat to the supply lines serving Allied forces in western Europe and were subjected to repeated air attack. This included four attacks by No. 9 Squadron and No. 617 Squadron of the Royal Air Force, during which a total of 53 of the five–ton, Tallboy earthquake bombs were dropped. There were also two attacks in 1945 by the American air force with rocket–powered Disney bombs, specialist weapons designed to penetrate fortified, concrete bunkers that could resist conventional bombs.
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