Kazemat, Betonnen werken Coupure Diefdijk-A2 Culemborg

English translation

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Description

Cluster 63.

NEW DUTCH WATERLINE

Introduction

CONCRETE BLOCK OF CAST-STEEL DOME CASEMATE TYPE G as remainder of linear and access defence with trench systems, group shelters and the like. In 1936, as a supplement to the reinforced concrete casemate, the so-called cast-steel dome casemate was introduced in the Netherlands, which was based on a system already applied in France in 1917. The armour domes used were small in size (favourable with regard to visibility and hit probability), circular in form (favourable with regard to deflecting hits and strength), relatively simple to produce in series, and they had an 'external' firing opening (favourable with regard to gases and noise). Moreover, they could be manufactured in the Netherlands, which significantly reduced dependence on foreign countries. A first order of 100 pieces in the Netherlands (from DEMKA) was followed by a second order of 50 pieces from the Belgian Soc. Anonyme John Cockerill. In total, more than 700 must have been cast in a short time, but only a few have survived. The cast-steel domes, with a diameter of 1.75 m and thicknesses of 10-17 centimetres, were installed in multiple casemate types with resistance classes W 12-15 to W 21-28.

Shortly before the start of the Second World War, so-called Cast-Steel Dome Casemates Type G were constructed at various locations in the Dutch lines, in particular in the Yssel Line, the Meuse Line, the Grebbe Line (each approximately 150) and the New Dutch Waterline (approximately 80). The usual construction of reinforced concrete with one or more fixed firing openings was abandoned in favour of a system that possessed a firing direction projectable within variable limits (up to 270°), within a cast-steel cylinder with dome roof. Most of the domes were placed in the Dome Casemates Type G. Cast-Steel Dome Casemates Type G were built according to a standardised design and consist of a cast-steel dome (usually removed), which is anchored in a reinforced concrete structure. On the front side there was a firing opening with a projecting part—an 'eyebrow' for protection of the weapon—and on the other side an entrance closable by a steel shutter. The concrete structure consists of a relatively low rectangular building, with a bevelled part on the front side, to achieve maximum field of fire. The standard armament for dome casemates in the New Dutch Waterline consisted of a heavy machine gun. The firing opening and access to the casemate could be sealed 'gasproof' from within.

During the Second World War, the vast majority of the domes inland were demolished by the occupier from the casemates—in part by blowing them up—to be recast for other steel requirements. On the coast, they were partly incorporated into the defence, but were mostly demolished after the war. As a result, complete dome casemates are rare, but they are found, among other places, still on the Fort at Vechten. The concrete structures in which they were placed are found more often—but usually in damaged form.

Description

The CONCRETE BLOCK OF CAST-STEEL DOME CASEMATE TYPE G (1939-1940) is the remainder of a relatively low, nearly square, concrete casemate (approximately 7.00 x 6.20 x 2.50 m; w x d x h), with a rearward sloping surface at the height of the space hollowed out in it for the dome. The surviving example within the Tussenstelling Diefdijk - Noord complex lies to the south of the Rijksweg 2 (A2), approximately 75 m south-southeast of Diefdijk no. 3. On the rear side an excavation in the concrete to allow the dome to be entered. The example has been blown up and as a result shows serious concrete damage; the dome has been removed and remelted. The example is not accessible.

Valuation

The CONCRETE BLOCK OF CAST-STEEL DOME CASEMATE TYPE G within the Tussenstelling Diefdijk - Noord complex is of general interest by reason of:

* Cultural-historical values as a component of the New Dutch Waterline as designed by C.R.T. Kraijenhoff and initially realised from 1815 by him, Jan Blanken and Major-engineer Willem Offerhaus, and subsequently by others for approximately 125 years strengthened and improved.

* Architectural-historical values, in particular as an expression of military-strategic architecture, which is based on the system of: a. the system of inundation and access defence (20th century), b. the race with strengthening offensive means (20th century), c. the system of 'living' field fortification in depth (20th century).

This concerns a component from the period 1939-1940, namely a reinforced concrete remainder of a standard cast-steel dome casemate.

* Ensemble value and situational values as a component of the New Dutch Waterline in general and by reason of the mutual functional, functionally-spatial and physical coherence with the remaining components of the complex and with the access of the newly constructed Rijksweg 2.

* The component is representative (characteristic) because it is clearly recognisable as a component of a dispersed defence line and as defence of a new access added to the existing fortification system and is also clearly recognisable as such in the field.

* The component is reasonably well preserved because important physical characteristics, despite deliberate partial dismantling, have remained recognisable.