Its primary task was to prevent enemy German shipping—chiefly submarines—from entering the English Channel en route to the Atlantic Ocean, thereby forcing the Imperial German Navy to travel via the much longer route around Scotland which was itself covered by the Northern Patrol.
The Dover Patrol was first officially established as an independent command on 12 October 1914 in response to the German capture of Antwerp and Zeebrugge, as well as the impending fall of Ostend.
[1] German possession of Belgian Channel ports and rising activity of U-boats led the British Admiralty to consider the Dover Straits vital enough to be distinct from the Admiral of Patrols.
With these resources it performed several duties simultaneously in the Southern North Sea and the Dover Straits: carrying out anti-submarine patrols; escorting merchantmen, hospital and troop ships; laying sea-mines and even constructing mine barrages; sweeping up German mines; bombarding German military positions on the Belgian coast and sinking U-boats.
Similar memorial obelisks stand at Cap Blanc Nez on the French channel coast, and at John Paul Jones Park near Fort Hamilton, overlooking New York harbour.