A mine used by defenders to intercept an enemy mine or tunnel.
Normally the threat would have been dealt with by means of a counter-mine, but the tunnel was now far too close for that.1990, Peter Hopkirk, The Great Game, Folio Society, published 2010, page 436:
2
An underground gallery excavated to intercept and destroy the mining of an enemy.
3
A stratagem or plot by which another stratagem or project is defeated.
Thinking himself contemned, knowing no countermine against contempt but terror.a. 1587, Philippe Sidnei [i.e., Philip Sidney], “(please specify the folio)”, in [Fulke Greville; Matthew Gwinne; John Florio], editors, The Countesse of Pembrokes Arcadia [The New Arcadia], London: […] [John Windet] for William Ponsonbie, published 1590, →OCLC:
countermine
verb
Etymology From counter- + mine.
1
To plot opposition; to frustrate the initiatives of another.
[…] every gamester will agree how necessary it is to know exactly the play of another, in order to countermine him.1749, Henry Fielding, chapter III, in The History of Tom Jones, a Foundling, volume (please specify |volume=I to VI), London: A[ndrew] Millar, […], →OCLC, book VI:
2
to sap hostile mining.
[…]so Fritz could sleep easily in his trench, so far as mines were concerned; and Fritz, confident in his Herr Professors, altogether neglected any attempt to counter-mine.1923, Frank Fox, “The Man-Made Earthquake”, in Charles Francis Horne, The Great Events of the Great War, volume 5: