Hegra Fortress - Ingstadkleiva Fort

Ingstadkleiva Fort

The fort's guns came from the dismantled Ørje Fortress in Marker. The artillery was made up of flat angle guns with a range of 6 to 9 kilometres (3.7 to 5.6 mi). The fortifications themselves consisted of 300 metres (980 ft) of halls and tunnels dynamited into the mountain at Ingstadkleiva, as well as trench systems and gun positions excavated from the rock with explosives. There are two main underground parallel tunnels of around 80 metres (260 ft) length, with a 35-metre (115 ft) tunnel connecting them at a straight angle. One of the main tunnels served as crew quarters while the other was in direct connection with the above ground artillery pits.

The fortress' artillery consisted of two 7.5-centimetre (3.0 in) and four 10.5-centimetre (4.1 in) positional artillery pieces in half-turrets placed in pits dynamited from the rock and lined with concrete, as well as four Krupp M/1887 field guns. The 8.4-centimetre (3.3 in) pieces, designed before the advent of recoil systems, were described by the Germans after the 1940 surrender as Napoleonic.

The positional artillery is placed in an almost straight line facing east, with a 20-metre (66 ft) distance between each 10.5-centimetre (4.1 in) gun and 16 metres (52 ft) between each 7.5-centimetre (3.0 in) piece.

To enable the fortress to withstand attack without support from outside a 5-to-8-metre (16 to 26 ft) wide barbed wire obstacle was constructed encircling the entire fortress.