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 >>/20398/
The success of this Gardening varied. On the lower part of the Danube where the river is flowing slow in wide bed and where maritime de-mining methods can be used it wasn't a great problem, but on the Hungarian section with the narrower, rocky, somewhat sinuous bed both general shipping and de-mining had lots of troubles. It is estimated that over 1200 mines were deployed and I believe beside the usual explosives (bombs, shells, etc.) they still find some up to this day.
My source material gives the following markings to the mines:
A-102 and A-180
B-202 and B-208
C-303 and C-306
But the British classification doesn't seem to comply to this:
http://www.navweaps.com/Weapons/WAMBR_Mines.php
I'm not entirely sure the identification of these devices. Supposedly the Germans layed mines at the mouth of the Thames, Brits gathered, studied and perfected them. Then used it as well.