sapping

Sapping is a military engineering technique used in siege warfare to approach and breach fortified positions. It involves digging trenches and galleries, known as saps, toward the base of a wall, typically under cover of protective fire. The aim is to create an avenue for assault or to undermine the fortification by weakening its foundations. The work is carried out by engineers and specialists called sappers or miners. A typical operation begins with a shallow sap and may extend into deeper galleries or a mining tunnel directed toward the target. If successful, the walls or foundations can fail, enabling an assault; defenders may countermined, collapse breaches, or destroy the approach.

Historically, sapping played a central role in many sieges from the early modern period onward. It demanded careful logistics, risk management to prevent collapses, and coordination with artillery and other siege tactics. The technique evolved with changes in fortification design and battlefield technology but remained a symbol of underground siege warfare in military tradition.

In modern militaries, the term persists in the designation of combat engineers as sappers, reflecting the historical roots of the occupation. Sapping also appears in a broader, non-technical sense as a verb: to sap can mean to drain energy, strength, or morale, and sapping describes the gradual weakening of an opponent or resource.

A related but distinct sense involves botany and forestry, where sap extraction from trees is typically called tapping rather than sapping; the latter usage is largely historical or literary and often avoided in technical contexts.