Pillboxes and bunkers

In the constructions some new fortification expressions were made: Galleries and caves.

The caves consisted of 12-15 cm reinforced concrete in the walls and 20-25 cm in the ceiling. Rocks were placed under 0.5-1 meter of earth for early detonation.
Each cave was equipped with a 40 cm. carbon floodlight  and two machineguns.
The purpose of the caves was to provide flanking fire on the barbed wire closures, so hostile infantry was shot at from the side while they forced the barbed wire entanglements.
The double caves were equipped with 4 recoil guns and 2 floodlights. They were angled, and had two flanking tasks.
Completely in the spirit of experiences and the huge losses this tactic had caused at the trenches on the battlefields of Europe.

There was at total of 29 pcs. single caves, 3 pcs. single caves with an observation stand.
Where the fields of barbed wire are angled, double caves were built. There were 7 double caves These 7 double caves are situated in the Karlslunde (5) and Tune(2) area.

The Caves were gradually replaced by so-called galleries, presumably because the large hole for the floodlight was too great a risk for the caves.
A gallery is an bunker with embrasures for 8 to 10 men with eigther riffles or machineguns.

Like the caves, the galleries had flanking tasks, but could also have frontal functions and thereby supporting an exposed salient position.
There were a total of 11 double galleries and 23 single galleries. The Ydinggaard Double Gallery is, as the only one, splitted in two halfs with 25 metres between the two halfs.