My interet in the Battle of Dakar comes from the guns on Goree Island
They came from a French battleship "Vergniaud " which was disarmed in 1922 and her 240mm guns handed over for coastal defence, nine being installed around Dakar. The ship was then used for target practice and finally scrapped on 27 November 1928
The two 240 mm cannons were taken from a Danton class battleship - Schneider armored turret. And there is an optical rangefinder as well.
And featured in seeing off a British task force at Dakar in 1940 (Aircraft Carrier, 2 battleships, 5 cruisers and a mass of destroyers in Operation Menace designed to frighten the Vichy French out of Dakar. Even had de Gaule himself along with the task force, but the shore batteries saw the British off, damaging a battleship.
The coast artillery in and around Dakar was controlled by II/6 RAC et Marine
9 x 240mm at Cap Vert
Batterie Mamelle 3 guns
Bie. Bel-Aire 2 guns
Bie.Cap-Manuel 2 guns
Bie. De Goeree 2 guns
4 x 155mm L/50 mle 1932 Schneider
Bie. de Yoff
8 x 138mm
Bie. de Goeree
Bie. Madeleines
(presumably 4 guns each)
8 x 75mm
3 sections defense des passes (2 guns each)
1 gun Mamelles
1 gun Cap-Manuel
It would appear that 9 of the 12 x 240mm guns from the Vergniaud were deployed around Dakar as shown above In fact when the French battleship in Dakar harbour Richelieu was hit by British shells, some of the gun crews from it moved to the shore batteries and were apparently better shots than the native gunners who had been manning them. But I have no idea which of the shore batteries hit any British ships, and probably the batteries themselves did not know.
The Richelieu itself only appears to have fired 24 rounds from its big guns, but I have no idea how many rounds the 240mm shore batteries fired.