a. Rectangular Shelter

A type of concrete shelter found on the Breton Peninsula in the vicinity of Quimper is shown in figure 24. It is 38 feet long and 19 feet wide, by exterior measurement. The interior height is reported to be 7 feet. Its walls are 39 inches thick. The roof is of the same thickness but is reinforced with steel bars, seven-tenths of an inch thick. On one side is an escape ladder, reached from the interior by means of an opening in the roof 27 inches square. This type of fortification is usually made with a loophole (the location of which is unknown), which is closed when not in use with a wooden frame filled with sand.

Each shelter has three or four ventilating chimneys with sandstone flues, and these are built out from the structure proper in order that there will be no weak sections in the walls. This tends to nullify the effect of grenades or other explosive charges that might be dropped into the chimneys, which also have many elbows or bends.

Figure 24.—Rectangular shelter on Breton coast.

b. Standardized Shelter

A concrete shelter that appears to have been standardized by the Germans and installed along the Channel coast is shown in figure 25. It will be noted that the overall thickness of the concrete, except for the 12-inch retaining wall at the emergency exit, is 3 feet 3 inches.

Figure 25.—Standardized shelter on English Channel coast.

c. Dune Shelter

Another type of reinforced concrete shelter, reported to be common in the "golden sand" dunes in the vicinity of Erquy, on the north central coast of the Breton Peninsula, is shown in figure 26. Shelters of this kind are buried in the dunes and camouflaged with turf. They are about 14 feet 8 inches square, with walls 2 feet 6 inches thick. The interior is divided by a concrete wall into two bays, each 4 feet 3 inches wide.

Figure 26.—Sketch of dune shelter.

Figure 27 shows a photograph of a shelter that may be a variation of the type described above. It was constructed at Nieuport, on the Belgian coast. The photograph shows it before it was covered with earth.

Figure 27.—Photograph of shelter built in dunes.

It is reported that the dunes between Mariakerke and Middlekerke in Belgium have been hollowed also, and that concrete shelters, probably of this type, have been built into them. Reports indicate that the Germans have installed batteries of guns up to calibers of 210 mm behind these dunes. Antiaircraft guns and antiaircraft machine guns are included in the battery positions. In some dune areas, the Germans have been compelled by the narrowness of the dune zones to dispose their batteries in straight lines, parallel to the beaches.

d. Ostend Shelter

The interior plan of a German shelter, apparently designed for the defense of important intersections within a city, is shown in figure 28. One of these shelters has been constructed in Square Stephanie, in the Belgian coastal city of Ostend. The roof and walls are about 6 1/2 feet thick, and the rooms are almost 7 feet high. The nature of the weapons at the main entrance and in the walls commanding the secondary entrances is not known.

Figure 28.—Ostend shelter.

e. Artillery Observation and Command Post

Figure 29 shows a type of combined artillery observation and command post. The dimensions for the interior are approximate only. There have been reliable reports of the siting of such shelters perilously close to the edges of cliffs. If this proves true, the foundations of the shelters might be undermined by gunfire directed at the face of the cliff below the shelter. There are, however, probably few instances of such sitings.

Figure 29.—Artillery observation and command post.