This was a British naval minelaying operation in the Heligoland Bight (September 1939).

The first offensive minefield, which targeted the exits from Germany’s main naval bases, was laid by the destroyers Esk and Express on 9/10 September, and between 11 and 29 September the minelayers Adventure and Plover, supported by auxiliary minelayers, laid 3,000 mines in the Strait of Dover. Escort was provided by the light anti-aircraft cruiser Cairo and the destroyers of the 19^th Destroyer Flotilla.