The fort has the shape of a trapezium : the small base is the headfront (A), the large base the gorge front (B) and both sides the side fronts (C) (fig.1). It is surrounded bya 40 to 50 m wide wet moat (D), preceded by a conterscarp berm(E) and a mild slope, the g lacis (F). There are two joined casemated caponiers (G) to defend the moat. On the superstructure of the fort, we find the infantry firing crest (H) and the turrets.
The entrance of the fort lies in the traditore battery (l) with on the left and right the gorge front building (J). A central corridor leads to the mainfront building (K). Light andfresh air come into the building bytwo inner courts. Several other corridors lead to the turrets and caponiers.
A fort is a part of terrain which has been organised in such a way as to give the defender a marked advantage over the attacker. lt is a preorganized part of a battlefield. It should follow the development of military technology, especially the state of the art of artillery.
Fort Liezele, built between 1908 and 1914, has the following characteristics:
At the time the fort was built, the heaviest siege gun was the French 27 cm mortar. The weight of such a gun was limited to a maximum of 5,000 kg by the capabilities of horse-drawing. Experiments show how thick the concrete walls should be to resist a 270 mm shell.
The Antwerp forts were built with following specifications:
Exposed walls are turned away from the direction of incoming shells and the windows can be protected with steel beams. The top layer (1,25 m) of the concrete of the vaults has 400 kg cement to the m3, the bottom layer only 180 kg/m3.
During the 1914 siege the Germans used 30.5 cm and 42 cm mortars in the sector of attack, which were moved by steam tractors. The forts were unable to resist such a pounding. A chunk of concrete of the intrados would be detached by the impact of a 30.5 cm shell, the vault would be pierced by the impact of a 42 cm shell.
Turrets protect the artillery of the fort. The turrets turn around a vertical axis and have a 360° field of fire. They are all of a same type, the Cockerill model 1909. The cupola has the shape of a segment of a sphere and is made out of 22 cm thick chrome-nickel steel. In order to keep the embrasures as small as possible the guns are mounted in a special way. A base armour protects the base of the turret and is in turn protected by a concrete rim. Experiments in 1912 at Otchakoff showed that the base armour was too weak to give sufficient protection. A new concrete rim was made of reinforced concrete. These works were not completed by 1914 as we can see at the fort.
Fort Liezele is a second category fort (a first category fort had more artillery) and contains the following artillery (fig. 2) :
Fig. 2. Main Arament
Due to the high cost of the turrets, as well as the necessary dispersion of the artillery, all the artillery was not installed in the permanent works. The artillery in the forts and redoubts were the so-called "permanent safety armament" of the fortress and should be able to stop a surprise attack. To stop a regular attack "supplementary safety armament" had to be installed in field works between and behind the forts. Additional "reserve artillery" would intervene, as soon as the actual attack sector was known.
For observation there are two armoured observation turrets (D) supplemented by mobile observation posts connected with the fort by field telephones.
In 1914 there was not enough ammunition to hold on for a long time
5.7 cm fast-firing guns flanking the moat were installed in the joined casemated caponiers (A) and in the ground floor or the traditore battery (B) (fig. 3). Six guns were flanking the main front, two each sidefront and two the left and right side of the gorge front. These guns were installed on a mounting bolted to the wall (fig. 2).
Two turrets for a 5.7 cm gun (C) were covering the bridge and shoulders. These 5.7 cm guns fired, with a rate of 20 shots a minute, two kinds of ammunition:
Four mobile 30 cm search lights illuminated the surrounding area. A few 5.7 cm guns on wheel-carriages and machine-guns which were stored in a bomb-proof shelter were also used for the defense. During the bombardment the infantry took shelter in the fort. They could man the firing crest very quickly, using the infantry exits in the front and the rear, and the slopes of the inner courts.
Fig. 2. Close defence
Much importance was attached to the flanking of the intervals between the forts and the redoubts, so as to create a continuous belt offire around the fortress (fig. 3). This was effected from the ground floor of the traditore battery (from Italian "traditore" or traitor, the "traitorous battery", who shot the enemy in the flank and the back..
Each flank contained the following items :
The guns placed on a mounting, bolted to the wall, used mostly shrapnel fire. The traditore battery was also the entrance to the fort, which was protected by a rolling bridge. The face ofthe gorge front was oriented in such away that the traditore battery guns could fire on the glacis of the next redoubt or fort.
Fig. 3. Grootflankement
The peace time manning of the fort, 50 men strong, was kept busy training and maintaining the works. ln time of mobilization the garrison was brought to its full strength, with reservists amounting to some 410 man, consisting of 200 fusiliers and 210 gunners. ln 1914 Fort Liezele had a garrison of about 300 men.
During a siege the service was organized as follows. The infantry was organized into three shifts of 24 hours, guard, picket duty and rest, relieved at 18.00 hrs. The gunners also had three shifts, lasting 12 hours, relieved at 06.00 and 18.00 hrs.
The soldiers had to be accommodated in the fort; they had their quarters, a kitchen, a shower room, latrines and even a jail. The officers had their own mess. There were besides the necessary store houses, two powder-magazines and an infirmary. The command post was located in the main front together with the telephone exchange and the commander's quarters. All the rooms were equipped with electric light and a combined shaft for ventilation and heating.
The power for the two electrical generators (39 kW under 70 V) was provided by two semi-mobile steam engines "SA des Ateliers de Construction de la Meuse", which were located in the two engine rooms. The power was used for operating turrets, searchlights, ventilation ofthe rooms and turrets and electric light.
The 26 telephones were connected with three exchanges (main exchange in the fire control room and two secondary exchanges in the observation turrets). Outside the fort there was a connection box for the sector and interval commanders, the surrounding works and the artillery observers.
In 1935-1936 it was decided to transform Fort Liezele into an infantry strongpoint, to be defended by amachine-gun company equipped with20 light and heavy Maxim machine-guns. The transformations were made from October 1939 till April 1940 under the supervision of Colonel Lefebvre of the Engineers.
The forts were in principle to be armed with four sections of heavy machine-guns and six sections of light machine-guns (a section of machine-guns had two machine-guns).
The casemates in the traditore battery and caponiers were adapted for installing the machine-guns. In the caponiers supports were constructed for the two legs of the light machine-guns. In the traditore battery "Chardome" supports were installed. Two of these Chardome supports can still be seen next to the rolling bridge and they consist of :
The embrasures used for the guns were reduced for the use of the machineguns.
The redoubts of Letterheide and Puurs were defended by one section of heavy and two sections of light machineguns.
To resist a gas attack the command post, the dressing station and two rest rooms were made gastight and provided with a ventilator, airfilter and gasproof armoured doors.
In several rooms the chimneys were checked while some new chimneys were built. In February 1940 the fort was connected with the electrical main of Puurs and the whole electrical installation in the fort was repaired. In March 1940 the ventilation system against war gases was operational and the filters were in place. This was done by the S.P.G. (Service de Protection contre les Gaz).
Some painting was done in March 1940 in the rooms, the officers' mess, non-commissioned officers quarters, other quarters. The removal of the earth on the roof and the asphalting took months of work. In February 1940 the holes of the former turrets were sealed off with reinforced concrete and covered with earth.
To protect the entrance a number of sandbags were held in stock in order to constructa sandbag wall. The rolling bridge received a check-up. Adaptation works in the kitchen and latrines were also carried out.
In wartime a supplementary defensive line was provided by refitting about 650 German bunkers, originally builtin 1917. Between the Scheldt and the Zenne there were about 125such bunkers, mainly shelters, observation bunkers and also a few machine-gun bunkers. This bunkerline was to be protected by inundations (e.g. of the Rupelriver).