Ouvrage Hackenberg

• Ammunition Entry Type A: Connects to military railroad, defended by one machine gun/37mm anti-tank gun embrasure (JM/AC37) and two automatic rifle cloches (GFM).[8]
• Personnel Entry: defended by one machine gun/37mm anti-tank gun embrasure (JM/AC37), one grenade-launcher cloche (LG), and two GFM cloches.[9]

• Block 1: infantry block, in front of the east wing, equipped only with a retractable machine gun turret.[10]
• Block 2: artillery block armed with a retractable twin 75mm gun turret and two automatic rifle cloches (GFM).[11]
• Block 3: armed with one 81mm mortar turret. An automatic rifle cloche (GFM) was tactically linked to the neighboring Ouvrage Mont des Welches as an observation point.[12]
• Block 4: infantry block with one retractable machine gun turret, 37mm anti-tank gun (JM/AC37) embrasure, one machine gun embrasure (JM) and two GFM cloches.[13]
• Block 5: eastwards-flanking artillery block with three 75mm gun embrasures, two automatic rifle embrasures (FM), two GFM cloches and one grenade-launcher cloche (LG).[14]
• Block 6: artillery block with one 135mm retractable gun turret and one GFM cloche.[15]

• Block 7 : infantry block, twin of Block 4 with one machine gun turret (JM), one machine gun/anti-tank gun embrasure (JM/AC37), one machine gun embrasure (JM) and two GFM cloches.[16]
• Block 8 : westwards-flanking artillery block with three 75mm gun embrasures and two GFM cloches.[17]
• Block 9 : an unusual artillery block, armed with one 135mm gun turret and a flanking 135mm gun embrasure to the west. Two GFM cloches provided local defense.[18]
• Block 10 : artillery block with one 81mm mortar turret and two GFM cloches.[19]

Two observation blocks are situated on the ridge of the Hackenberg, which gives its name to the ouvrage

• Block 11: equipped with a periscope-type observation cloche (VDP) and a GFM cloche.[20]
• Block 12: with a periscope-type observation cloche and two GFM cloches.[21]

Apart from Hochwald, Hackenberg is the only ouvrage in the Line with a deep anti-tank ditch and wall. The ditch is defended by Blocks 21 and 25.

• Block 21: located at the eastern extremity of the ditch, this infantry block is provided with one machine gun/anti-tank embrasure (JM/AC37), one machine gun embrasure (JM), one 50mm mortar embrasure and one GFM cloche.[22]
• Block 22: an infantry block in the angle of the ditch with one machine gun/anti-tank embrasure (JM/AC37), one machine gun cloche (JM), and a GFM cloche.[23]
• Block 23: a small block armed with two GFM cloches and a grenade-launcher cloche (LG).[24]
• Block 24: a large infantry block in the western angle of the ditch, with a machine gun/anti-tank gun embrasure (JM/AC37), a machine gun turret (JM), a 50mm mortar turret and two GFM cloches.[25]
• Block 25: a mixed block for the defense of the anti-tank ditch with a 75mm gun embrasure, a machine gun embrasure, a 50mm mortar embrasure and a GFM cloche.[26]

The rail switching area in the interior of the ouvrage, near the munitions entry. This area allowed munitions trains to exchange between diesel locomotives (outside) and electric locomotives (inside the fort).

In addition to the extensive network of connected combat blocks, a series of detached casemates and infantry shelters surround Hackenberg, including

• Abri du Hummersberg: Subterranean infantry shelter (abri-caverne)[nb 2] with two GFM cloches.
• Casemate du Hummersberg Nord: Single block with one JM/AC37 embrasure, one JM embrasure and one GFM cloche.
• Casemate du Hummersberg Sud: Single block with one JM/AC37 embrasure, one JM embrasure and one GFM cloche.[28]
• Casemate de Veckring Nord: Single block with one JM/AC37 embrasure, one JM embrasure and one GFM cloche.
• Casemate de Veckring Sud: Single block with one JM/AC37 embrasure, one JM embrasure and one GFM cloche.
• Abri de Veckring: Subterranean infantry shelter (abri-caverne) with two GFM cloches.[29]

German troops harassed Hackenberg in 1940. A portion of the front was at this time held by the British 51st (Highland) Infantry Division, along with the French 26th and 42nd Infantry Divisions.[28] No attempt was made by the Germans to directly attack this central portion of the Maginot Line, the Germans preferring to go around the west end of the Line and take it from the rear. Hackenberg provided covering fire to other ouvrages in the area through June as the Germans advanced eastwards behind French lines. On 15 June the German 1st Army broke through the Line at the Saar and pushed west and east along the Line, enveloping the French armies.[33]

The ouvrage remained under French control for a time after the armistice of 25 June 1940. Hackenberg's garrison evacuated on 4 July 1940.[34] Following the takeover, French prisoners of war were put to work removing mines around the ouvrage, resulting in many French casualties.[35] In the following years under German occupation, Hackenberg was used as a bombproof factory[36] by the Klöckner-Humboldt-Deutz company of Cologne for the production of transmissions and gears. The operation used the M1 magazine and the caserne, sharing the magazine with German munitions.[37]

During the Occupation, the Germans occupied Hackenberg and posed a considerable obstacle to American advances in 1944 during the Lorraine Campaign. Although much of Hackenberg's armament had been removed for use in the Atlantic Wall, some of the heavier guns remained. On 15 November, the U.S. 90th Infantry Division encountered Hackenberg as it advanced along the length of the Maginot Line. Block 8, with its battery of 75mm guns, proved particularly troublesome, with 99 rounds falling on the American position in 90 seconds.[38] After an attack using tank destroyers failed, the Americans used a 155mm self-propelled gun against the rear of Block 8 in the morning of 16 November. The success of this attack allowed the Americans to take the west wing on the 17th. Hackenberg was entirely occupied by American forces on the 19th, only after the retreating Germans had destroyed the M1 magazine.[39]

Following World War II, interest revived in the use of the Maginot Line to defend against a possible Soviet advance through southern Germany. Funds were allocated for restoration of the gros ouvrages, with new 105mm artillery proposed for Block 8 at Hackenberg. Funding was not forthcoming, and work was limited to restoration of systems and improvements to existing armament. Restoration of Block 8, damaged in the American attack of 1944, was canceled.[40] The renovations did not include the command post or the barracks.

By 1956, Hackenberg had been designated part of the Mòle de Boulay, a strongpoint in the northeastern defenses against Soviet attack.[41] By the late 1950s interest in fixed fortifications was waning after France developed a nuclear deterrent. The money needed to maintain and upgrade the fortifications was diverted for the nuclear programs. Hackenberg was maintained for use by the Army until 1968, and finally abandoned in 1970 after it was placed in second-class reserve.[7][42]

In 1975,[43] residents from nearby villages started to organize sightseeing tours, which led to the founding of the volunteer-driven AMIFORT association for the preservation of Hackenberg.