Not many people would know about the air war with the aerial mines that the Germans deployed against shipping it became so bad that it nearly broke Englanduntil they got their hands on one and successfully deloused it a great feat of steel nerves.
Of course the Germans made a fundamental mistake with the magnetic & magnetic/acoustic in so much in the self destruct firing circuit they made the sliding part out of the same metal as what it sat in allot of them failed to go off due to the fact of the block binding on the slide had they made it out of different materials then they would have a 100% success rate.
The chaps who deloused these things and there were many different types including the booby trapped mines with the Zus 40 which grabbed the main fuse as soon as it was attempted to remove the main fuse the Zus 40 set the 1 tonne warhead off if they tripped the fuse then they had 17 seconds to get 400 yards away from it try running that distance in that time!
All were RNVR and could only get the George cross as they were not facing the enemy, but thy surely did face them on the mud flats, in gasometers in pitch blackness after being lowered into it, upside down reaching out of site on an ammunition barge when the fuse started to run that chap beat the fuse by a margin that could not be measured in his mind he fled but stay and do his duty he did.
One instance burrowing into a earthen dam wall over a 4 day period getting pulled out backwards by a sapper with rope tied to your ankle with the spoil from digging only to find when you reached the mine the fuse was on the opposite side then having to burrow over it and delouse it underground laying over the mine.
One mine in particular gave them trouble "GEORGE" the only way into the mine was through the tail and inside the tail were photo electric cells as soon as daylight hit them the warhead detonated they were lucky one wrecked itself on the docks allowing them to discover its secret the Germans used filtered light to assemble the mine, also it had the worlds first printed circuit ever made yes the Germans developed it not Japan.
The book is called Softly Tread The Brave By Southall I have read it 3 times and it contains far more than I have time to type here infact some of the mines were so dangerous it scared the Germans, the only one they never defeated was the oyster mine but the book is well worth getting.