Submarines were based in the Camber during WW1, indeed the reason for constructing the Camber was as a small harbour-within-a-harbour to afford protection for submarines and small craft from the wilder sea conditions in the exposed outer harbour.
I would imagine that they saw very little action as the Dover Strait would be an impossible submarine operating area with shallow water, banks, strong currents, etc. Also very little to attack as the German big ships only ventured out on very rare occasions. Additionally, they would have been extremely likely to have been attacked by our own side as the Dover Patrol mustered a huge anti-submarine effort attempting to deny German submarines passage through the Dover Strait.
Probably based there as one element of defence should the German High Seas Fleet head south towards the Thames or Dover Strait, with the Grand Fleet having to come down from Scapa Flow and Rosyth.
http://shipsintheportofdover.fotopic.net/c1554060_1.html
There were no submarines based in Dover in WW2 for the reasons above. A destroyer flotilla was based here to begin with but had to be withdrawn after suffering heavy damage and the loss of the flotilla leader, HMS Codrington, whose wreck remained on Dover Beach for the rest of the war. Also the ammunition ship HMS Sandhurst was badly damaged and the oiler War Sepoy was sunk.
With the Germans occupying the French coast, Dover was exposed to aerial attack from Stukas and medium bombers, and later from the cross channel guns, and was totally untenable for anything other than light naval forces. Accordingly MTB's, MGB's, M.L.'s, Air Sea Rescue launches, etc, were based here. The headquarters was at the Lord Warden Hotel, requisitioned as HMS Wasp, and initially most of the craft were berthed in the Train Ferry Dock.
The reinforced concrete shelter dubbed the "Submarine Pens" was constructed in the Camber to afford better protection for the light naval forces mentioned. I would imagine completion would have been in 1940/41. Where the appellation "submarine pens" came from is unclear. They are of similar construction to the submarine pens the Germans built in WW1 at Brugges and elsewhere, and to the ones they built in WW2 in the Bay of Biscay ports and back in Germany. Everybody would have been familiar with those from WW1 and, seeing something similar being erected in the Camber, perhaps those not in the know surmised that was what they were intended for.
