HISTORY




AA Searchlights on the Normandy Beachhead
By Captain Frederick W. Eggert, Jr.
Coast Artillery Corps
Reprinted from Coast Artillery Journal, Vol. 89, No. 1, Jan./Feb. 1946


   To the 225th Searchlight Battalion was assigned the mission of furnishing illumination for the air defense of the entire Normandy beachhead. Although the organization had been extensively trained in fighter-searchlight tactics in the United States, it had considerable experience in gun tactics while participating in the Air Defense of Great Britain and consequently was prepared to operate in conjunction with automatic-weapons and gun units in the defense of the beachhead.

   The advance party began its reconnaissance of positions on D+6 (12 June 1944), confronted by sniper and land-mine difficulties. Of the two, mines were the most serious for the positions selected were principally in the heavily mined areas. The defense contemplated in the original plans called for a normal circular defense of one battalion with lights 6,000 yards apart. This presented an unusual problem in that it assigned to a single battalion an area normally covered by several searchlight battalions. The circle was to consist of two concentric rings, 6,000 yards apart. All radar-controlled searchlight sections were to be on the outer ring, the inner ring consisting of searchlight sections only. The normal ring defense contemplates a defended object no greater than 2,000 yards in diameter. Here the area was approximately 18,000 yards by 12,000 yards. Atmospheric conditions in this part of France being somewhat unfavorable, it was realized that no great concentration of light could be placed over any one given point in the entire defense. With these problems in mind, the reconnaissance proceeded and all sites were selected.

   It was determined that this attempt to defend the entire beachhead with a single battalion was impractical and more would be accomplished by restricting the objective to several small but vital points. Highest defensive priority was thereupon given to airstrips then operational or in the course of becoming so. It was anticipated that any enemy air attacks would be executed from very low or low altitudes or would be in the form of strafing attacks. To accomplish this end one platoon was to be deployed about each airstrip, thereby insuring a maximum of six lights per airstrip although no more than three lights would be used on any single target. The platoon organization was well fitted to this plan and by eliminating the normal 6,000-yard interval a compact and effective defense could be attained.

   Since the type of enemy attack anticipated was from a low level there would be no necessity of gun-searchlight operations. Consequently, searchlight illumination was to be used in conjunction with automatic-weapons units solely and at a maximum slant range of 8,000 yards. This being the plan, one platoon could illuminate all avenues of possible approach and effect an illumination well before the hostile plane reached the defended point.

   The tactical disposition of the elements was built about two offset triangles. The inner triangle was to consist of three searchlights only. At either end of the airstrip, 200 yards from the landing mat a carry light was placed. The third carry light was placed to the airstrip flank, 800 to 1,000 yards from the center of the strip. The lights at the end of the strip were placed well to the flank and subsequent incidents justified the necessity for this. No possible obstruction to landing or departing aircraft could be permitted and though caution was used in placing these lights to the side, on several occasions bomb- laden fighter-bombers barely missed these lights by a matter of feet.

   From the disposition of the three carry searchlights, it was possible to obtain complete coverage of the strip and the adjacent area. If necessary, these three lights would place a canopy of light over the strip either to home a lost aircraft or to furnish illumination for automatic-weapons fire. A further function of these lights was to illuminate the strip proper if so requested by the airstrip commander.

   The three radar-controlled searchlights of the platoon were to be placed in the outer triangle and, if possible, were to offset the inner-triangle searchlights. The radar- controlled lights were to be approximately 2,000 yards from the strip with the same interval between lights. By off-setting the outer lights, any possible dead or obscured avenues of approach were eliminated.

   The main difficulty in siting these radars was that considerable mutual interference was to be expected. Later events showed this fear to be wholly without foundation, for the sets operated extremely well under the circumstances. The absence of interference may well be due to the density of the now famous Normandy hedgerows which would have been more accurately described as tree rows. The advance party in selecting these radar sites did its utmost to find those having a certain amount of terrain mask but the flat nature of the countryside made this almost an impossibility. A few sites had some mask, but the great majority had nothing but flat, heavily wooded terrain.

   To appreciate the problem of preparing positions is to understand the nature of the well- known Normandy hedgerows. In fact, they are not hedgerows in the American sense of the word, but rather a line of thick, close trees and bushes. Every field is bordered with them. The trees are by no means small, often towering to 70 or 80 feet. A natural line of sight was therefore difficult if not impossible to find. Cutting down a single row of trees would not solve the problem, for beyond that row were more fields with more rows of trees. To overcome these obstructions and to attain a five-degree line of sight which would permit illumination of low-flying aircraft at maximum range, towers were erected for both the searchlight and distant electric control station.

   The towers for searchlights were four feet in height; those for the control station were six feet. Construction of these towers was mostly of sandbags with a center of short logs. A number were erected by building a platform across the hedgerow, using the stumps of fallen trees as columns. The searchlight was rolled into a truck or prime mover, which, in turn, backed up to the platform and the searchlight was rolled on to it. The control-station towers were built with sandbags in the center of fields and securely wired down to prevent toppling.

   Though much hard labor was necessary to build these towers, later results fully justified the effort for the five-degree line of sight was obtained. Many of these excellent results would not have been attained had it not been for the cooperation of the Corps of Engineers in furnishing the services of their bulldozers and power-saw units. Their invaluable assistance enabled the rapid construction of these towers and made it possible for this organization to become operational with the least possible delay at a time when illumination was urgently needed.

ENEMY ACTIVITY


   Upon becoming operational on D+12 (18 June 1944), it was discovered that the initial estimate of the enemy's probable tactics proved to be incorrect. Contrary to expectation, most enemy activity was from intermediate altitudes and on a few infrequent occasions from low altitudes. This also was a change from the earlier enemy tactics in Normandy when more attacks were executed from very low level with little concern about cloud cover.

   It is not possible to disclose the number of illuminations of enemy aircraft made by this organization. However, the number was not great due to the enemy's failure to fly on clear and cloudless nights and his wide use of natural cover. If the night was clear, there was very little enemy activity. When a plane ventured from cover and was illuminated, violent evasive action was taken immediately. A prolonged illumination under these circumstances was extremely difficult. Once the plane entered the cloud bank, the cloud's density prevented further illumination. The distance a hostile plane strayed from his cover was small. On one occasion, an enemy aircraft was illuminated for an instant and immediately dove vertically into a cloud bank.

   During the first two weeks of the Normandy campaign, the greatest number of enemy attacks occurred at either dusk or just before dawn. In the beginning it was virtually SOP (standard operating procedure) for the enemy to appear at the moment our fighters were landing at their bases. Later on, however, this activity greatly declined.

   Experience in this campaign has shown that the German pilot has a far greater fear of searchlights than American pilots. The latter do not become as panicky as the enemy nor are their evasive actions as violent as those of the enemy. Evidently the German pilots still remember their costly encounters with searchlights during the Battle of Britain. It is often a trait of human nature to overestimate one's own accomplishments, but from enemy activities before and after the arrival of searchlights, this organization cannot help but believe that it materially contributed to rendering ineffective enemy activity over the Normandy beachhead.

   Another escape used almost as widely as cloud cover by the enemy was that of "window," which is simply the dropping from aircraft of strips of tin foil which interfere with radars by clouding the scopes. On nearly every occasion that enemy aircraft was present in the area, window was detected in the same vicinity. These attempts at interference had little if any effect for this organization had been well trained in countermeasures while operational in the Air Defense of Great Britain. Interference countermeasure training more than proved its worth, for the primary purpose of window, the element of surprise, was totally absent.

   The continuous flow of intelligence is a matter of vital importance to higher echelons. This battalion — by its dispersed setup — was able to observe all activity in its area and the intelligence furnished by it proved to be of considerable value. Frequently, data was reported well before any notice thereof was given by other echelons or by long-range warning systems.

   Whether or not the further development of radar will eliminate the necessity for searchlights is a matter for future study. However, the role played by searchlights in the Normandy campaign and subsequent campaigns has more than warranted its presence in this theater. Many AAA outfits can boast of the number of enemy aircraft destroyed by them, but few can lay claim to having saved as many of their own planes as this battalion. These searchlights have been welcome sights for many an American pilot lost or in distress. Its contribution to the discouragement of German pilots was material and its facilities for transmission of "on the spot" intelligence were of no mean importance in determining the nature of any activity in the vicinity. Considering all of its diversified activities, the searchlight played a major role in making the defense of the Normandy beachhead impregnable.

LESSONS LEARNED
  1. Automatic-weapons and gun units much be impressed with the necessity for fire discipline when operating in conjunction with searchlights. It was found that frequently when a searchlight went into action on an aircraft many fire units immediately commenced firing as a matter of course even though the target had not been illuminated, or, if illuminated, had not been definitely recognized as hostile. This was especially true when two lights formed an intersection with or without an illuminated object. Fire units must hold fire until recognition is assured.
  2. All AAA units equipped with radar must be well trained in operating in the face of enemy attempts at interference. Such training should be a prerequisite for complete unit training, for it was observed that enemy air activity was invariably accompanied by some attempt at artificial interference with radars. There will be little, if any, surprise upon the unit's operating personnel if this anti-interference training has been adequate.
  3. Units in training must be impressed with the importance of clear, concise, and rapid transmission of spot intelligence regardless of how important the incident may seem to the individual observing it. Higher echelon may be able to fit the seemingly unimportant fragments of information into a clear picture of some enemy endeavor. Many troops are prone to transmit only that information that seems important to them personally.


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