Undermining
From Wikipedia, the freeencyclopedia.
Undermining was a technique employed during the Middle Ages to bring down castles and other fortifications. The technique was used when the fortification was not built on solid rock, and was developed as a response to stone built castles that could not be burned like earlier-style wooden forts. A tunnel would be excavated under the outer defenses either to provide access into the fortification or to collapse the walls. These tunnels would normally be supported by temporary wooden props as the digging progressed.
Once the excavation was complete, the wall or tower being undermined would be caused to collapse by filling the excavation with combustible material that, when lit, would burn away the props leaving the structure above unsupported and thus liable to collapse.
External link
- Castles of Britain page about castle undermining
Undermining (also known as Removal of the Guard) is a chess tactic in which a defensive piece is captured, leaving one of the opponent's pieces undefended or underdefended. The opponent has the unpalatable choice between recapturing or saving the underdefended piece. When using this tactic, however, one should keep in mind that the opponent can sometimes sacrifice the piece whose defence is being undermined before capturing the piece which just took the defender.
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Kramnik-Topalov in the seventh round of the 2004 Linares chess tournament reached the diagrammed position with White to play. The black knight on a4 is defended only by the black pawn on b5. White undermined the knight with 1.Bxb5. The game continued 1... Rxb5, 2.Rxa4, with a net material gain of a pawn for White.
See also algebraic chess notation.
