La Batterie du Poste Optique
The Batterie due Post Optique was built in 1898 to mount four 138 mm guns, model 1873-4. This is a barbette battery with four emplacements separated by traverses that contain the magazine. The guns had a maximum range of 7,500 metres with a rate of fire of one round per minute. The guns have now gone, but one of the 1897-gun mounts remains on site.