Excavations started on 28 December 1940 and the first gun arrived on 25 March 1941, although their best-known action came a few months later, on 12 February 1942, when the light battleships Gneisenau, Scharnhorst and the heavy cruiser Prinz Eugen attempted the Channel Dash from Brest back to Germany. The K band radar at South Foreland started to track the ships of the Brest Group coming up the Channel towards Cap Gris Nez. At 12:19, the first salvo was fired; since maximum visibility was five miles, there was no observation of fall of shot by either sight or radar. The "blips" of the K-set clearly showed the zig-zagging of the ships and full battery salvo firing began without verifying fall-of-shot. 33 rounds were fired at the German ships, which were moving out of range at 30 kn (35 mph; 56 km/h).
Initially it was thought that four hits had been made, but the Germans revealed that all had missed. By the end of the war the four guns had expended 2,248 shells, most in the months before and after the Normandy landings. 28 enemy ships were confirmed sunk between all the coastal batteries around Dover and the deterrent effect was significant