ChessRanger
Tactics

Undermining

also 'removing the defender'

Attacking or exchanging the piece or pawn that defends a key point.

If a square, piece, or mating net is held up by a single defender, you don't attack the point — you remove the support. Capture it, chase it, or deflect it, and the thing it protected falls.

Undermining a pawn chain means striking at its base: knock out the pawn that supports the head of the chain and the whole structure crumbles.

Why it matters

'Remove the defender' is one of the most common tactical ideas — spotting the single overworked guard wins material again and again.

The mistake everyone makes

Battering a well-defended point head-on instead of asking 'what defends it, and can I take that away?'

Related terms

Deflection
Forcing an enemy piece away from an important duty so something it was guarding falls.
Overloading
A piece given more defensive jobs than it can perform, so removing or distracting it collapses the defence.
Combination
A forcing sequence of moves — usually with a sacrifice — that wins by force.
Pawn structure
The arrangement of the pawns, which shapes the plans available to both sides.

See Undermining in your own games

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