The Maginot Line - A misunderstood history

Cupola GFM Model 1929, type A

Observation/machinegun cupola

This first produced model of this cupola was also the most numerous one.
GFM stands for Guet Fusil Mitrailleur (observation and machine gun). In the context of the Maginot Line, Cloche is French for an armoured cupola. The main visual characteristic of the cupola is the rectangular embrasures (3 to 5 in total).

Made of cast armoured steel, the cupola, just like the B model, was used for observation and close-in defence.
For this purpose, it was armed with an FM Mle 24/29, or a 50mm mortar Mle 1935.

An episcope and a bloc jumelle A cloche mounted F1 periscope A bloc jumelle

For observation, an episcope (a miniature periscope), a periscope (there were several types available) or a bloc jumelle were used. Most GFM cupolas possessed a fitting in the top through which the periscope could be raised.

Several models
  • PM (petit modèle = small model)
    On casemates with protection levels 1 or 2.
  • PMA (petit modèle allongé = small lengthened model)
    On casemates with protection levels 1 or 2. This armoured cupola sometimes replaced the PM when more declination of the armament inside was required due to it’s position relative to the casemate.
  • GM (grand modèle = large model) on combat blocks with protection levels 3 or 4.
  • GM two-piece.
    Exclusively used in mountainous areas on combat blocks with a protection levels 3 and 4.
Dimensions
Height Outer ø Armour Weight
PM
(petit modèle)
1.70 m 1.60 m 0.20 m 10,5 t
PM
(petit modèle)
taller
2.70 m 1.60 m 0.20 m 17,0 t
GM
(grand modèle)
2.70 m 1.80 m 0.30 m 26,0 t
GM
(grand modèle)
modular
2.15 m 1.70 m 0.25 m 17.0 t

A type F1 periscope In some cases, when a GFM cupola was used as an auxiliary observation cupola for artillery, an observer could scan the surroundings with a periscope type J2 (enlargement 7x). In other cases, a type F1 (for PM) or F2 (for GM) were used (for less precise, general observation).

A characteristic feature of all GFM type A cupolas are the ear-like lifting points on each side. These were used to move/lift the cupolas into place during installation.