When the Germans invaded France and Belgium in 1940 both these armies still had WW1 Renault Ft-17 tanks in operational service. They were obsolete and could not knock out a German Panzer III tank. During the occupation old tank turrets were removed and incorporated in the German Atlantic Wall defences.
The Atlantic Wall Renault FT tank turret at Le Grand Bunker Museum in Ouistreham Normandy (Tourelle de FT-17 tank)
The le Grand Bunker Museum in Ouistreham is set in the middle of a residential area about 500m south of the coast. It is at the junction of the Avenue du 6 Juin with the Avenue de la Plage. When entering the address into your Sat-Nav device use the Avenue de la Plage road name.
I have found a problem with entering the number 6 in the Avenue du 6 Juin road name on different devices a problem; some want the number 6 and others want the letters six.
All round vision was poor in these defensive tank turrets. They only had tiny slits in the armour plating.
Deployment in Normandy 1944
These tank turrets were known as Turmstellung (tower points). They were installed on top of thick concrete bunkers that were normally covered over with earth and grass. The only visible point of this defensive system to an attacking enemy was the small tank turret. They were tiny targets and proved difficult to hit. Some were only armed with machine guns but others like this one kept their Puteaux SA 1918 37mm gun.
In World War One this gun was designed to be used against infantry, machine gun posts and fortified locations. It was not designed at the time to fire on other tanks. The Puteaux SA 18 gun's armour penetration power was poor. In 1944 it could only deal with infantry, soft skinned vehicles and lightly armoured Allied half tracks. It could not penetrate the front armour of a Sherman, Churchill or Cromwell tank.
Rear view of the Renault FT tank turret Turmstellung
Not all the tank turrets had working guns installed. They were used to provide armoured protection for artillery observers who would radio or phone gun crews at different points within the network of defensive bunkers, new target locations.
The gun was reliable and had a high rate of of fire thanks to its semi-automatic breech loading system. It could easily be operated by one German soldier and there was a low incidence of the gun jamming. It could fire 15 rounds of 37mm ammunition a minute and had a muzzle velocity of 600 metres per second with APCR ammunition. The gun was made by Atelier de Construction de Puteaux in France.
A late version of the WW1 Renault FT tank fitted with the Puteaux SA 18 cannon instead of the normal machine gun.