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8. Reserves

This chapter is about operational reserves -- a concept that has received little attention in discussions of air operations. The fact that it receives little attention indicates one of two things: Either the conventional wisdom is correct, in assuming that the subject of "reserves" is not applicable to air war, or that it has been ignored mistakenly and is in fact quite important.

Our hypothesis is the latter.

On 16 May 1940, Winston Churchill made a desperate trip to Paris, where he asked the French high command overseeing the hasty retreat of its forces in front of the German offensive through the Ardennes, "Ou est la masse de manoeuvre?" ("Where are the reserves?") the answer was, "Il n'y a aucune!" ("There is none!")131

Just months after the disaster in France, Churchill was in the command post of Number 11 Group watching the progress of the Royal Air Force (RAF) defense against the greatest German raid to that date on London. He had just seen Air Vice Marshal Park commit his last six squadrons to the battle and simultaneously call on his neighboring commander, Air Vice Marshal Leigh-Mallory for all his forces. Churchill asked Park what else he had in reserve. Park answered, "Nothing." All his forces had been committed.132

Reserves May Help Better the Odds

The theory of reserves is not easy to grasp, especially on an emotional level. We are inclined to feel that a unit not committed to the battle somehow is not pulling its weight. We tend to think of Henry V's injunction of, "Once more unto the breach, dear friends, or close up the wall with our English dead." We think in terms of gathering our strength and charging the objective with everything we have. We accept, perhaps on a visceral level, the theory of concentration and mass, and interpret this theory to mean all of our resources.

We calculate ratios and, never quite comfortable with our superiority (or lack thereof), want to make the odds better. We add more forces in the belief that we are increasing our chance of success or decreasing our chance of failure. In a certain sense, none of these thoughts is entirely wrong; in fact, in a perfectly predictable world, each might be entirely right. But if the world were perfectly predictable, war would never happen. The antagonists, knowing the outcome by virtue of mathematical analysis, would sign the armistice terms before the first bullet flew. War is, of course, an intensely human activity. It defies prediction. That reason is a key to why reserves came to be so important for land warfare.

Clausewitz spoke of the fog of war, the friction of war, and the uncertainty of war. Nothing can eliminate these hindrances to perfect action, but reserves can ameliorate their negative consequences in at least two major ways. First, they provide a commander the wherewithal to exploit an error or failing by the enemy. He can pour into the battle masses of fresh troops who have the potential to break remaining enemy resistance and force a retreat or rout. On the other hand, reserves can be thrown against an enemy attempt to exploit a commander's own error. The arrival of strong, fresh forces may break the enemy attack and restore the line -- whether actual on the ground or conceptual in the air.

The point could be made that a sufficiently smart commander ought to be able to anticipate either of these situations, and put requisite forces into action at the start of the battle. A certain theoretical validity can be given to this argument -- although the uncertainties of war make the move from theory to practice virtually impossible. What the argument ignores is that the introduction of reserves in effect creates an entirely new battle, or at least a distinctive new phase.

Up to the time when reserves enter the fray, the opponent is dealing with relatively known quantities doing relatively obvious things. Reserves immediately increase the uncertainty factor by dramatically changing the quantitative and maneuver equations. In other words, the impact of the sudden appearance of a new division on the battlefield is entirely different from the impact that same division would have made had it been on the line from the onset of action.

Fog and friction are hindrances to one's own action, but to the extent that they can be inflicted on the enemy commander, they become allies. Reserves can help in this process because their mere existence means the enemy commander must take their possible employment into account. Since he doesn't know where they may be committed -- or whether a given commitment is a feint or real he must spend time thinking about them. And he probably will have to deploy his own forces somewhat differently than he would if no reserves faced him.

Subsumed under the broad concept of reserves are some rather elusive principles on how they should be used. Elusive is the only applicable word, for they amount to such useful exhortations as "do the right thing!" A noble expression to be sure, but one difficult to enact. One of the more popular, and actually more valuable, principles applied to reserves is the injunction against committing them piecemeal. This principle has been taught in military schools for centuries -- and it has been ignored time after time with normally disastrous results.

Shock Value of Reserves Can be Valuable

Explaining why reserves should not be committed piece-meal is not too difficult: Reserves seem to be most valuable when their appearance shocks enemy troops and commanders. Actually, the mental shock to the enemy may be more important than the physical effect of the reserves. A physical effect, though, can be explained by the principles of momentum. Momentum is a product of mass and velocity. Assuming a constant velocity, the momentum, the force with which something strikes, will be in direct proportion to its mass.

Combining the moral and the physical, we can see why committing reserves piecemeal makes little sense. Piecemeal commitments, because they are incremental, lose much of their ability to induce confusion and fear in the mind of the enemy. Adapting to a gradual change in a situation is far easier than to have to adapt to a sudden and massive change. Second, its potential momentum, and thus its physical shock power, is reduced proportionally to the division of the reserve into small parts.

The next two principles for the use of reserves are simple to state: Don't commit too soon, and don't commit too late.

Clearly, determining what is too early and what is too late must be a highly subjective process. It may even be a work of sheer artistry or genius. The idea is that any battle -- or even an entire war -- has certain points where the situation is precarious enough, or close enough to equilibrium, that the application of a new force will have an effect all out of proportion to its comparative size. Judging that point or moment is not easy.

Confederate Gen Robert E. Lee thought it had arrived when he sent Gen George E. Pickett across a mile of open terrain on the third day of the Battle of Gettysburg.
Lee guessed wrong -- and lost a battle and doomed his cause. Conversely,

Lin Piao made a perfect decision on committing the Chinese -- in the sense that China constituted a strategic reserve for the North Koreans -- against MacArthur. A few weeks earlier would have required extended lines of communication against a still concentrated American force, while weeks, or perhaps even days, later would have found MacArthur dug in and massed on the south banks of the Yalu.
Timing is everything.

The examples cited and the analogies drawn have so far been from land war. Are the principles applicable to air war? In very broad, theoretical terms one would conclude a priori that they must be. Certainly, the minds of enemy airmen and their commanders are subject to shock, just as are the minds of ground soldiers. Likewise, the physical principle of momentum applies as much in the air as it does on the land. The question is, however, whether the theory translates to practice.

Sortie Not Flown is Not a Sortie Lost

Flyers have a saying that notes graphically how useless is runway behind them, once their aircraft has touched down for landing. A similar view suggests that a sortie not flown is a sortie forever lost. A general feeling exists that aircraft are to be flown as frequently as maintenance requirements allow, and that a target of some sort will be there for each sortie. These ideas produce a general belief that the concept of reserves does not apply to air operations. In fact, few historical instances exist where air was consciously kept in reserve.

Two exceptions, however, are fascinating. One actually took place during the Battle of Britain, and the other was planned, but never occurred, in the air battle over Germany. Let us review both.

The Battle of Britain began on 8 August 1940, when the Germans opened a campaign in earnest to seize air superiority over Britain to prepare the way for an invasion.133 The fighter forces opposing each other were roughly equal, but for the British fighters, the German bombers were the target. The Germans had about as many bombers as the British had fighters so, in total, the Luftwaffe outnumbered the Royal Air Force (RAF) 2 to 1.134
(This ratio ignores the British bomber command which, although two-thirds the size of its Luftwaffe counterpart, did not make any serious attacks on German fighter bases and thus played no direct role in the Battle of Britain.)

Despite the numerical superiority of the Germans, the British commander,

Air Marshal Dowding, kept about a third of his fighter forces away from the battle zone, where they were not subject to attack. Neither could they participate in the war. The British maintained a reserve even during what Churchill called Britain's darkest hour. On top of this, Dowding's two subordinate commanders, Park and Leigh-Mallory, maintained their own reserves.135
These reserves, Dowding's strategic reserve and the sector commanders' operational reserve, played a key, if not decisive, part in winning the battle for Britain and averting an invasion.

Until the first week in September, the Germans conducted an amateurish attack on Britain that was characterized by shifting objectives from fighter bases to production to shipping. They had failed to follow up on the first day's strikes against British radar. They tried escorted and unescorted bombing missions. When their fighters did accompany the bombers, they used close escort tactics. They frequently failed to concentrate or to coordinate raids on the same day. Despite all these errors, they were making progress. The RAF was beginning to suffer badly.136

Then, at the end of the first week in September, Hermann Goering, Nazi Germany's air chief, made a momentous decision which Hitler fully endorsed.

The British, some days earlier, had carried out a militarily insignificant raid on Berlin. An infuriated Hitler agreed to shift the focus of his attack on Britain from military targets to London. Many in the Luftwaffe were pleased with the decision that they had been urging for the past two weeks. They thought that it would force the RAF into a decisive battle.137
They neglected, however, the other side of the coin: By concentrating the Luftwaffe on London, pressure on fighter fields would subside and, more importantly, the British themselves could concentrate against the Luftwaffe. more effectively.

The Germans finally decided that the time was right for the final blow.

Every aircraft that could be made serviceable was to participate in a coup de grace planned for 15 September. The British, in part through Ultra intercepts, knew that the Germans planned their big thrust for the 15th. Consequently, Dowding used his strategic reserve to bring every fighter unit in Park's and Leigh-Mallory's sectors up to strength. He also put fewer than the usual numbers of fighters in the air on 14 September, leading the Germans to think they were winning, and also giving Fighter Command a chance to prepare for the next day's action.138
On 15 September, the British met the Germans in mass. Park committed his operational reserve of six squadrons and asked that Leigh-Mallory bare his sector in order to send all of his forces south to hit the Germans. Leigh-Mallory not only did so, but some of his forces attacked in full wing formation.
As a result of the British use of reserves (and mass), the Germans suffered such heavy losses that they concluded the RAF was so far from being beaten that the Luftwaffe did not have the time or resources to do the job. Within days they shifted to useless night bombings of London.139

Air Reserves Won the Battle of Britain

Commitment of air reserves had won the Battle of Britain, had precluded a German amphibious invasion, and in many ways had turned the tide of the war.

Three years after the Battle of Britain, the American daylight bombing campaign was beginning to cause the Germans problems. As previously noted,

The German commander of fighter forces, Adolf Galland, had decided that having a 3 or 4-to-1 advantage over the attacking bombers was necessary, to be able to inflict militarily significant losses on them.
(This decision was made before American bombers had fighter escorts for missions over Germany!)

Because of requirements on other fronts, Luftwaffe' fighter strength in Germany was too low to achieve ratios of fighters-to-bombers of much more than 1-to-1, and that only occasionally. Galland on three occasions proposed to Goering and Hitler that new production and newly trained pilots be withheld from the defense of Germany until sufficient strength was on hand to meet the Americans with at least 3-to-1 superiority. His first plea, in the spring of 1943, included a suggestion that fighters be withdrawn from other fronts; his plea was rejected on the basis that it might lead to lost ground in Russia or in North Africa.140

Galland made his next request the following spring. He proposed pulling all fighters out of France to concentrate them against the American bombers. Goering refused again, this time because of the expected invasion.141

During the summer of 1944, American bomber attacks became intolerable. Obviously, to men like Galland and Albert Speer, organizer of war production and forced labor for Nazi Germany, the war would be lost if something were not done about the bombers. Therefore, Galland again proposed building a huge reserve for commitment on a single day. He intended to assemble and train this force to put 2,000 fighters in the air on the first day in late fall that the weather was suitable. His objective was to destroy 400 to 500 bombers, with a probable loss of about the same number of German fighters. He believed that one or two days of such losses would make the Americans stop the bomber campaign for an extended period. During that time, Galland hoped his country would have sufficient respite to bring the new jet fighter into service, to restore aviation fuel production, and to train enough new fighter pilots that the Americans would face overwhelming odds when they resumed the campaign.142

Would Galland's plan have worked? There is a high probability that it would have.

In the fall of 1943, the American bomber offensive was called off after the 12 to 16 percent losses suffered in October. A loss of 400 to 500 bombers would have been equivalent to a 25 to 50 percent loss rate. Such losses would have seriously damaged virtually every participating unit. The shock itself, after a long period of declining losses, would have been dramatic to flyer and commander alike. The proposed ratios of 4-to-1 would almost certainly have been adequate to accomplish the job. Why didn't it work? Very simply, Hitler disbanded the reserve and committed it in support of the 1944 Ardennes counteroffensive.143

There, operating in a strange environment in bad weather, flying missions for which it had not trained, and committed against dispersed targets of only tactical importance, the reserve disintegrated. And so was wasted Germany's last hope to avoid destruction.

Reserves Can be Applicable to Air Operations

These two examples from World War II would seem to suggest that air reserves can be of extraordinary importance. Also, they show that the theory of reserves can be applicable to air operations. Do they mean that there must always be an operational or strategic reserve? The answer to that is not clear. The US Air Force has never kept a reserve (although in a sense, its production capacity gave it a strategic reserve in World War II). One could say that its unbroken string of victories since 1943 suggests that it did not need a reserve. Of course, in every conflict since then it has been on the offensive (even if highly circumscribed in Korea and Vietnam), with overwhelming numerical superiority. The two air forces in our examples were on the defensive and were numerically inferior. Reverting to our theoretical discussion, we recall that reserves seem to be most useful when the situation is unstable and susceptible to being unbalanced by the addition of a new force.

These observations would lead us to suspect that air reserves then are most needed when the enemy is equal or somewhat stronger than oneself.

In addition to the theory and examples cited above, some work done with computer war games suggests the utility of air reserves. A brief explanation of one game will help. The simulation started with an enemy numerically superior on the ground and in the air making attacks across a broad front, but more strongly on some areas of the front than on others. The first step of the game was to see how close air support sorties should be apportioned. It turned out, as an exponent of concentration might have expected, that putting the majority of close air support against a particular enemy thrust was far more beneficial than spreading it out over the entire line.

The next step was to examine the possibility that close air support might be more effective on day two or three -- or even later -- than it was on day one. Before detailing that trial, it is necessary to discuss the initial assumptions on how close air support would be used.

The standard assumption is that as many close air support sorties should be flown as possible on day one. Thereafter, a decreasing number will be flown because of attrition. On a graph, this system would show up as a descending line, starting at a high number on day one and falling to a relatively low number at so many days into the future. In real life, the line might not be straight; rather, it might be a descending sine wave reflecting surge capabilities and other factors. Nevertheless, the straight line probably is not a bad approximation for average outcomes.

What can be done to change the graph?

Several different schemes for using sorties are possible. First, no sorties could be flown until day two or three. Then, the graph would look the same, but it would start two days to the right of the ordinate. Ignoring possible destruction of aircraft on the ground, this provision would mean that the full weight of close air support would hit the enemy on his second or third day of operations. Under some circumstances, the sudden onslaught of previously unseen close air support might have as much of an impact on enemy operations as commitment of a large ground reserve. The idea of holding ground forces in reserve for a period of time is well accepted. Should air forces be treated differently?

Second, the line could be kept horizontal by deciding on some level of sorties that could be maintained over time. Although that level clearly would be much less than maximum surge capability, it would be higher at the end of the period than if a standard approach were used.

The last theoretically possible variation is an ascending line, on which sorties on day one start out at a very low level and increase over time. Attaining the same number of sorties on the last day as could be achieved on the first day with a maximum effort is not possible, for obvious reasons. However, flying more sorties on the last day than would be available using the other schemes is possible.

War Efforts Come in Surges

One benefit from varying the sortie pattern comes from the prediction that not every day of battle is equally important for oneself or for the enemy. In fact, effort in war comes in spurts and surges, rather than some inexorable pressure like a flowing river. Lulls between enemy offensive or defensive surges offer opportunities that can be exploited if force is available to do so.

The theater commander would like to be able to concentrate ground and air power to take advantage of these opportunities, but he can't if close air has been expended in some mechanical way. Thus, a sortie may be more valuable on one day than on another. And a sortie that is available on a later day because an aircraft was not previously lost in combat or is not down for needed maintenance may not be a wasted sortie by any means. Indeed, a sortie saved is worth more than a sortie rashly used. The computer game tended to show that a concentration of sorties, made available by holding back in the beginning of the battle, could be beneficial.

So far, we have discussed producing reserves by rearranging sortie production patterns. The same obviously can be done by holding units out of the battle, as the British did in 1940. One counter argument is that air, because of its mobility, can be shifted quickly from one chore to another and thus constitutes its own reserve. In theory, that may be true. But in practice, at least when the situation has been tense, no one has been willing to relinquish the support he was receiving from air. As we earlier mentioned, the Germans on the Russian front had devoted most of their air effort to close support. They finally realized that their air support should be striking behind the lines, and actually shifted it to do so. The cries of anguish from ground commanders were so loud, however, that the new mission was quickly aborted.144

The commander with numerical superiority has a better chance of shifting effort than the commander who must strain to do the minimum things that need doing. The beauty of an air reserve, controlled by the air component and theater commanders, is that it can be thrown in without taking anything away from anyone. Lastly, great advantage can be gained, as the British discovered, if some system allows the rotation of battle-weary units off the front to allow them to rest and recuperate.

Historical examples are too few and far removed in time to establish the absolute need for air reserves. With the theory added, however, the case seems at least strong enough to merit a commander's consideration, especially if he expects to meet a numerically superior foe.