During the mobilisation of 1939/'40 it was decided to reinforce Fort IJmuiden which had been between 1882 and 1890. The work included the construction of several light casemates. One of them was a type S7. This means that it has seven embrasures for a light machine-gun or a rifle. It is the only Dutch casemate that survives around the fort, a similar type with 5 embrasure was demolished some time ago. The S7 defended the southern flank of the fort and had to prevent an enemy landing here.

During WW II the German took heavier measures to defend IJmuiden.They built several bunkers around the fort, including a special one for a depth charge thrower. You can see it on the photo left of the S7 casemate. The depth charges had to prevent enemy subs to enter the port of IJmuiden. Since the port was only attacked from the air the system never served.