A recurring and often little-noted item of news is that "mines were laid in enemy waters." Here, broadcast by a Flight Lieutenant on minelaying duty, is an account of what that operation entails.
The other night we set off in one of our bombers for those enemy waters in which our mine was to be laid. A mine is really a sort of delay-action bomb dropped into the water. You see it flop out of the aircraft and go sailing down on its parachute. It sinks into the water very quietly; no flame, no flash, no leaping debris such as a big bomb might make. The mine just sits there waiting. Just think what it means to the enemy, that night after night British aircraft buzz round that long coastline from Narvik to Bordeaux, along which its convoys must go carrying the products of occupied Europe. The convoys must hug the shore, or else our bombers, motor torpedo boats or submarines will get them. But along those shores, in the shallow waters, our minelaying aircraft have been at work the night before.
It was a dirty night on which we went out, with cloud down to within a few hundred feet above the sea. We flew above it. The trouble with flying above cloud like that is you may not be able to tell where you are, and your mine must be dropped just where you want it. However, for us that night the question largely solved itself.
As soon as we reckoned we were off the enemy coast we began to see searchlights and flak. Those of our crew who had been in these parts a good many times before had little difficulty in fixing our position. Soon we found a flak barrage going up to the port as well as to starboard. That told us definitely where we were. Down through the cloud we went, lower and lower. At last we came out of the greyness, and then just a few feet below was the sea, rough and brown and cold, and too near for comfort. Back we went into the cloud.
Immediately I heard the bomb-aimer's voice over the inter-com: "Bomb doors open." Then I heard a clonk as the mine was released. Then the bomb-aimer's voice: "Bomb gone," the pilot's voice: "Bomb doors shut." On the way home I thought, "Well, it's there."
Probably, of course, the enemy knows that these channels are now dangerous, but, if so, it means that all his convoys will have to put in to port. For days, probably, a fleet of his minesweepers will have to come out seeking for what we've dropped. Maybe they won't find it, maybe our mine will be detected and swept up. But then, just as the channels are clear again, the next dark night they will hear the drone of our bombers. They will wonder if all those channels aren't dangerous again. And maybe they will be, or maybe somewhere else will be.
Then they'll have to decide whether to send the convoys through and risk half-a-dozen laden ships going to the bottom, or start their sweeping all over again. For this is one of the great advantages of dropping mines from aircraft. A minelayer or submarine can't revisit a minefield once it's been laid; if it did, it would probably be blown up on its own mines. But an aircraft can come back and back, keeping up the supply, laying more mines just after the enemy has swept up the old ones. - The Listener