Undermining is attacking the pawn or piece that supports an enemy structure, so that once the support is removed the thing it was defending becomes weak or falls.
Many positions are held together by one key defender — the base of a pawn chain, or a pawn guarding an advanced one. Undermining goes after that support rather than the target itself, because once the prop is gone the whole structure sags.
The classic case is a pawn chain: you can’t easily attack the head, so you strike at the base. Remove the base pawn and the pawn it was defending is left hanging, and the chain collapses from the bottom up.
It overlaps with ‘removing the defender’, but undermining specifically targets the foundation of a structure. The habit to build is to ask, before attacking a pawn or piece, ‘what is holding this up, and can I take that instead?’
Attacking the pawn or piece that supports an enemy structure, so that removing the support leaves the defended target weak or lost.
Strike at its base rather than its head. The base pawn holds the chain up, so undermining it makes the advanced pawns fall.
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