Fort Hackenberg is generally held to be the largest Gros Ouvrage of the Maginot Line. with seventeen combat blocks as well as the two protected entrance blocks. The underground passages are reported to extend to over 10 km. Our guide Quentin spoke perfect English and took us on what I would judge to be the best tour of the weekend. Construction of the fort started in 1929 and was finished in 1935. It protected the approaches to Metz, being part of the Fortified Sector of Boulay. The contours of the land mean that the armaments are in two groups, with a valley between; at its maximum the galleries are an impressive 96m deep. Early plans would have doubled the size of the fort but never saw fruition.
Our tour took us through by-now familiar elements starting through the ammunition entrance, now labelled with its original designation of A19. The 60mm railway extended outside the fort and could have transported up to 240 tonnes of ammunition per day. Unlike Fermont, which we visited the previous day, the topography allowed for the main galleries to be sufficiently protected without a descent by lift or stairs from the entrance blocks. To the left of the main passage lies the main (M1) ammunition store with nine separate bays for the different calibre weapons - ranging from small arms through 37mm anti-tank right up to 135mm shells. The overhead hoists are missing from the M1 access tunnel as the Germans made modifications to convert part of the complex into an underground armaments factory. They also blew up the third bay of the magazine on their retreat from the fort in 1944.
Blast Door Damage Leaving the magazine we passed through a substantial blast door weighing around 8 tonnes; it was slightly modified to allow plant for the German factory to pass through. The door still shows the effect of the blast wave of the massive explosion from the German destruction of part of the magazine. The railway overhead catenary originally had a break while passing through the doorway but today the power line is continuous.
Up to 1,200 troops occupied the fort and moving deeper in we passed the kitchen area, learning that each soldier was entitled to half a litre of wine a day. There was also beer on tap for those off duty; consumption is reported to have peaked in November 1939 when the fort’s garrison was boosted by the secondment of 51st (Highland) Division - part of the British Expeditionary Force. The fort was one of the last French units to surrender following the June 1940 armistice.
Much of the rest of the barracks was destroyed as part of the German factory conversion and most of the area has been converted into an impressive museum. The impressive plant area is substantially unchanged, apart from the upgrading of the generators by NATO in the 1950s (the fort was nominally repurposed as an underground hospital but never commissioned) and removal of asbestos exhaust piping. As well as the exhausts, there was lots of other pipework, including diesel, heating, water and air. Each generator used 60 litres of diesel per hour so three months supply demanded huge storage tanks.
Riding the Metro We next boarded the underground railway, arguably even more authentic than Fermont as the original catenary wires had been retained. Our journey took us to the western set of fighting blocks, a total distance of around 1.5km. Around a kilometre into the journey the tunnel to the eastern fighting blocks branched off. These are a further kilometre distant but have not been visited for many years due to geological problems. These seem to result from the swelling of a layer of gypsum which has caused distortion and collapse. We disembarked the train at block 9. which houses a 135mm mortar turret. The option of the stairway or original lifts was on offer to ascend 40 metres - many of us chose to do one in each direction to maximise the experience. We had been told that the depth of each step reduces towards the top of the stairway to ensure that tiring troops could maintain the same step rate and not delay those ascending behind. A return trip with a tape measure is called for to prove this construction detail! The drop down half door closing the lifts wouldn’t pass current health and safety legislation but it was good to see it hadn’t been modified.
The 135mm mortar or howitzer turret (the French name of lance-bombe translates literally as bomb-launcher) was on three levels with the controls being on the middle level. Below lay the counterweight and above was the ‘business end’. Targets were selected and elevation and bearing signalled through from the control post 40 metres below. It took a total of 21 soldiers to load and fire the weapon.
Fully operational Turret We were delighted to find that the weapon was fully operational both in the rise and fall of the so-called ‘eclipse’ turret and in its rotation through 360 degrees. This was fully demonstrated to us, showing a very smooth and impressive operation. The very same turret was demonstrated to King George VI during his visit to Hackenberg on 9 December 1939. Combat block 9 also held a more conventional 135mm weapon which fired through an embrasure. We briefly viewed this including the empty shell hopper of which more anon. We then took a trip outside through a blast door and over the diamond ditch.
On the surface we could see how little was visible above ground of the weapon in its resting position. The armour in the turret is over 35cm thick and the whole mechanism weighs over 160 tonnes. As we positioned ourselves round the turret, Quentin signalled into the fort and the mechanism was once again demonstrated for us so we could see it magically rise and rotate through a full 360 degrees. The fort saw some action in May 1940 and was one of the last positions to yield to the Germans after the armistice was signed, finally vacating the fort on 4 July.
We walked above ground to combat block 8, whose firepower consisted of three 75mm guns. The front of the block was badly damaged by incoming shells; fired however not by the Germans but by the Americans during their liberation of France. Germans within Hackenberg fired from this casemate onto the US 3rd Army on 14 November 1944; more than 90 shells arrived in around 90 seconds and clearly the threat had to be eliminated.
On 16 November the US Army responded with 155mm self-propelled guns and with accurate firing put block 8 out of action. Block 8 posed a particular threat as it was one of the blocks whose armaments faced towards France to counter a flanking attack. However these France-facing blocks usually had thinner concrete (1.5 versus 3m thick) to provide a weak spot to aid in the retaking of the fort, which worked to America’s advantage.
Helter Skelter We re-entered the fortification via block 8 and again had the option of descending via the original lifts or stairs. Those who chose the stairs were able to view the helical chute - to all intents and purposes a helter skelter - down which spent shells were despatched. Once at the level of the main communications passage we re-boarded the train and made a reluctant return to the ammunition block entrance.
A small shop at the exit sold mainly publications - including an excellent guide in English - raising money for the volunteer group who open the fort. They acquired Hackenberg in 1975 after NATO had vacated and provide a first-rate experience for visitors.