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Defeat In Detail

It has long been a principle of military strategy that one must not divide one's force in the face of an equal or superior enemy. A divided force risks defeat in detail, in which each part of the force is engaged by the full force of the enemy in turn and easily defeated.

By the 1900s mathematicians had worked out formal models for combat, and these yielded the square law of combat effectiveness. According to this law, the combat power of a force is equal to the square of the number of the units in the force, all other factors being equal. If a force x fights to tbe death with a smaller force y, then when the smaller force is annihilated, the larger force will be left with a strength of  (x2-y2)1/2.

If equal forces are engaged and fight to the death, both are annihilated. But if the second force is divided in half, and the first force engages the two halves of the second force one at a time, then at the end of the first engagement the first force will still have 87% of its original strength. After the second engagement, the first force will still have 71% of its original strength. It will have annihilated an equal enemy with 71% of its own strength intact solely because it remained concentrated while the enemy force was divided.

This mathematical model of defeat in detail describes continuous fire of a large number of guns on each side against the other. It does not take into account differences in force quality, the possibility of surprise, the confusion of battle, and other factors that might affect the outcome. The model also breaks down when firepower takes the form of a small number of highly destructive attacks, such as massed air strikes or torpedo attacks. For this reason, there was considerable disagreement among early aircraft carrier captains and admirals on the best tactics in a carrier engagement. Fleet exercises and war games suggested that, once discovered, a carrier would be rapidly disabled by enemy air power, and so most American naval leaders initially favored dispersion of carriers so that the discovery of one would not mean the destruction of all. The destructiveness of air strikes against a carrier was thought to be so great that there was no point in massing air power; naval air tacticians advocated "wave attacks" that would individually be sufficient to disable individual enemy carriers, one at a time, as they were discovered.

However, the availability of radar reduced the potential for surprise and increased the effectiveness of fighter defenses to a point where successful defense against an enemy strike seemed possible. Frederick Sherman advocated task forces of two carriers, to mass local air defenses and better coordinate multi-carrier strikes. On the offensive side, the early carrier battles showed that estimates that a single carrier air group could disable up to three enemy carriers were grossly optimistic, and wave attacks suffered high losses to the defending fighters. By the time of the Guadalcanal invasion, Frank Fletcher declared that he desired to "present the maximum number of planes (particularly VF) to the enemy at one time" to "thin out enemy VF opposition" and "not give him the opportunity of attacking our incoming planes in piece-meal fashion" (Lundstrom 2006).

The Japanese were already massing carriers when war broke out, and their experience at Midway led the other way, to increasing the dispersion of their carrier forces. This often backfired, as at the Battle of the Eastern Solomons, but they persisted in these tactics through the Battle of the Philippine Sea. At Leyte Gulf, their carriers were sacrificial decoys, and massing them to make a juicier target for Halsey made as much sense as anything.

On a grand strategic level, the Japanese perimeter defense invited defeat in detail. No one island in the perimeter was likely to be attacked by anything other than a massively superior Allied force, and the Japanese lacked the means to rapidly shift forces to the endangered sector, in spite of their advantage of interior lines of communication.

References

Hughes (1986)

Lundstrom (2006)

Marston (2002)



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