Defence in depth
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Defence in depth (also known as deep defence or elastic defence) is a
Strategy
A conventional defence strategy would concentrate all military resources at a
Defence in depth requires that a defender deploy their resources, such as
The defence in depth strategy is particularly effective against attackers who are able to concentrate their forces and attack a small number of places on an extended defensive line.
Defenders that can fall back to a succession of prepared positions can extract a high price from the advancing enemy while themselves avoiding the danger of being overrun or outflanked. Delaying the enemy advance mitigates the attacker's advantage of surprise and allows time to move defending units to make a defence and to prepare a counter-attack.
A well-planned defence in depth strategy will deploy forces in mutually supportive positions and in appropriate roles. For example,
The disadvantages of defence in depth are that it may be unacceptable for a defender to plan to give ground to an attacker. This may be because vital military or economic resources are close to the front line or because yielding to an enemy is unacceptable for political or cultural reasons. In addition, the continuous
Examples
A possible early example of this came at the
Edward Luttwak used the term to describe his theory of the defensive strategy employed by the Late Roman army in the 3rd and 4th centuries AD.
Later examples of defence in depth might be European
In the American Revolutionary War's Battle of Cowpens, the American forces were positioned in three lines which soaked up the shock of the British charge and inflicted heavy casualties before the Americans were able to overrun the British who, at this point, had lost their cohesion.
More recent examples of defence in depth include the multiple lines of trenches of the
The Pacific Theatre also had many examples of defence in depth, with the Japanese inflicting heavy casualties on the Americans in the Battles of Tarawa, Saipan, Peleliu, Iwo Jima, and Okinawa.
The best modern example of a successful defence in depth is that of the
Colonel Francis J. Kelly discussed the employment of defence in depth in
While untested, this was also the planned NATO strategy in Europe during the Cold War at the Fulda Gap.[citation needed] However, by the 1980s, West Germany eventually pressured NATO to abandon this orthodox doctrine as it would have entailed allowing the country to be overrun by Warsaw Pact forces before they would be finally stopped. Instead, NATO agreed to an alternative doctrine of "Forward defence," which was criticized for not only being militarily senseless that would have quickly forced NATO to resort to tactical nuclear weapons when Warsaw Pact broke through with their considerable conventional forces, but also that enemy considered the doctrine so provocative and potentially aggressive that striking first seemed a viable option as a result.[2]
Application to other fields
The concept of defence-in-depth (DiD) is also applied in the fields of life-threatening technologies where it is critical to avoid a disaster, or to save lives.
The safety of nuclear reactors and radioactive waste repositories also fundamentally relies on multiple systems and redundant barriers. The principle of redundancy is essential to prevent the occurrence of dramatic failures and in case where a failure would develop to retard the progression of a potentially disastrous event and to give extra time for taking again the control of the failed system. Ultimately, if a failure cannot be avoided, DiD also contributes to mitigate the consequences and to attenuate the negative impacts of the failure.
Defence-in-depth is required to guarantee the robustness of vital systems, e.g. in nuclear technologies and for aerospace systems where safety is critical. The DiD approach can be applied to any sensitive technology: submarines and naval systems, biotechnology, pharmaceutic industry, informatics, bank and financial systems, etc.
In nature, the immune system of most evolved organisms also appeals to multiple lines of defence in case a pathogen would defeat the first line of defence of cells, tissues and organs.
The robustness of the scientific method also relies on multiple lines of evidence and multiple lines of reasoning: strong claims require strong and multiple evidence. The repeatability and the reproducibility of experimental and calculations results are essential to guarantee their robustness and correctness. This associated with the scientific questioning and a constant interrogative attitude is at the core of the self-correcting process guiding the science.
Academics from Oxford University's Future of Humanity Institute also applied the concept of defence in depth to designing strategies for the prevention of existential catastrophes, especially those involving human extinction.[3]
See also
- Bandwagoning
- Culminating point
- Deep operation
- Defence in depth (non-military)
- Defense in depth (nuclear engineering)
- Defence-in-depth (Roman military)
- Hedgehog defence
- List of military tactics
- Loss of Strength Gradient
- Scorched earth
- Strategic depth
References