Defence in depth

Defence in depth is a military strategy sometimes also called elastic defence. Defence in depth seeks to delay rather than prevent the advance of an attacker, buying time and causing additional casualties by yielding space. The idea of defence in depth is now widely used to describe non-military strategies.
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The siting of mutually supporting defence positions designed to absorb and progressively weaken attack, prevent initial observations of the whole position by the enemy, and to allow the commander to manoeuvre his reserve. 1/3/83

Organisation des positions défensives s'appuyant mutuellement et destinées à absorber et affaiblir progressivement une attaque, à empêcher l'ennemi d'effectuer une observation initiale de l'ensemble du dispositif, et à permettre au commandant de faire manoeuvrer sa réserve. 20/11/96