Undermining

Undermining attacks the support of a position instead of striking the visible target first. If a piece or pawn is safe because another unit protects it, the attacker captures, exchanges, or threatens that defender. Once the support disappears, the target becomes undefended or inadequately defended.

The idea is common in pawn chains, diagonal groups of pawns that protect one another. Attacking the base may weaken several pawns at once. A pawn lever, a pawn advance that creates contact with an enemy pawn, can produce the capture needed to destroy that base and open lines for the pieces.

In many sources, undermining and removal of the defender are synonyms. Here, undermining emphasizes the support relationship, especially in pawn structures, while removal of the defender names the direct capture of the protecting piece. The concrete position matters more than the label.