The whole area off this section of the coast, up to about twenty miles to seaward, was included in the danger zone of the coast batteries. No vessel could maintain her position in that area, under ordinary conditions of visibility, for more than a few minutes at the outside limit. The reader may consider, however, that a ship desiring to attack the coast would merely have to approach in foggy weather or under cover of darkness. In foggy weather she would be unable to locate her objective--so that can be ruled out. At night she might conceivably arrive within a few thousand yards without being seen or heard. {38} But immediately she was located by the defences the latter would fire their star-shell and switch on their searchlights. The whole area would thus be illuminated like daylight. The vessel discovered under such conditions would probably be blown to pieces within five minutes. Thus it is manifest that ships cannot approach a hostile coast, in the face of modern defences, under the ordinary conditions of daylight or darkness, or in fog. We will now consider the mine problem. The German mine-fields extended to a distance of several miles from the coast. We had reason to know of their presence; from time to time, as reported in the press, our vessels had been blown up. Mine-fields off one's own coast provide a certain measure of defence. But they are also an embarrassment in that one's own vessels cannot pass through them, when approaching or leaving harbour, unless safe channels are kept clear for the purpose. This applied to the mine-fields under review. [Sidenote: The German Mine-fields]