The combat blocks

The Ouvrage de Schoenenbourg possesses six combat blocks – the primary platforms from which the fort’s garrison would engage the enemy. Each block essentially consists of a reinforced concrete core sitting atop concrete piles linked to the main gallery by a service lift and stairway. The concrete core was covered with earth with only the turreted armament and observation posts above ground, thus providing maximum protection against heavy artillery.

Blocks 1 and 6 are infantry casemates and would have been armed with two twin machine-guns which could be replaced with a 47mm anti-gun if required. Their task was to engage enemy units directly attacking the fort at medium and close range.

Block 2 is a machine-gun turret with Block 5 being designed to house two 81mm mortars in a rotating turret. These mortars, (an example of which can be found in the lower levels of one of the combat blocks), could fire up to 18 rounds a minute up to 3,500 metres. Increasing or decreasing the volume of discharge gas in the firing chamber altered the range.

At the heart of the forts’ defences were the two twin 75mm R32 guns located in rotating retractable turrets in Combat Blocks 3 and 4. Although seemingly few in number for such a large fort, the high rate of fire and accuracy of the R32 guns more than made up for their small numbers. Each twin mounting could fire 20 rounds a minute up to a range of 9˝ kilometres. Ammunition was brought up in two hoists – one for each gun from magazines labelled M1 and M2. Altogether each artillery turret weighs 189 tons of which 100 tons is the mechanism to rotate and raise/lower it.