The Germans use a large number of searchlights in connection with the AA defense of Germany and important installations of occupied countries. The searchlights have not been particularly successful in illuminating high-flying hostile bombardment planes at night for the sole benefit of gun units. The Germans have learned, however, to use their searchlights for other purposes. Searchlight crews are known to have been dipping their light beams to indicate to their fighter planes the direction in which hostile bombers are flying. Searchlights have also been used successfully to produce "dazzle" and "glare" in efforts to blind and confuse hostile pilots, bombardiers, and gunners. There is now no doubt that all these uses are proving a big help to the Germans in protecting their cities and strategic centers.

b. Equipment

As has already been indicated, the main searchlight equipment used by the Germans consists of the 150-cm (heavy) and the 60-cm (light) searchlights. The latter type is primarily for mobile employment with light Flak batteries. In addition to these two main items of equipment, the Germans also have a limited number of 200-cm and a few French 230-cm lights which are used to supplement the main equipment. Except for mass employment, initial data for the heavy searchlights are usually obtained through the use of sound-locators. With the development of radio-location equipment, there may now be a special set for use with searchlights, but no exact data is available on the extent of development in this field. It should be noted that the light searchlights use no sound locators, picking up their targets by definite searching patterns.

c. Location of Searchlights

Searchlights may be laid out in belts or in concentrations on likely lines of approach to important targets, and around or near gun-defended areas. German searchlights are used to aid night-fighter interception, and those at or near gun target areas are also used to cooperate with Flak. In gun-defended areas, searchlights are used to illuminate aircraft for Flak and for dazzle effect. The spacing of searchlights is as follows:

(1) In belts.—A belt usually consists of 10 to 15 or 20 to 30 searchlights, 1,000 to 2,000 yards apart along the course of the belt. The remainder of the lights are 5,000 to 6,000 yards apart.

(2) In concentrations.—When used in this manner, searchlights are usually spaced 2,000 to 3,000 yards apart in the shape of a triangle, a circle, or two concentric circles.

(3) In gun-defended areas.—Normal disposition is an even spacing approximately 3,000 to 4,000 yards apart. In some special areas, there are small groups with searchlights not more than 1,500 yards apart.

d. Searchlight Tactics

(1) On cloudy nights.—Unless a hostile airplane breaks through low-hanging clouds, only a limited number of searchlights, in belt or otherwise, go into action. They attempt to follow the course of the aircraft along the base of the clouds in order to indicate its course to fighters or in order to produce an illuminated cloud effect against which the aircraft might be silhouetted for the benefit of fighters or the AA artillery.

(2) On nights with considerable ground or industrial haze.—When the searchlight beams are unable to penetrate the haze, searchlights occasionally go into action at a low angle of elevation on to the haze. They thus diffuse and produce over the target area a pool of light through which the crews of attacking aircraft find identification and orientation extremely difficult.

(3) On clear dark nights.—When in belts to aid fighter interception, the most usual functions are: to illuminate the target; to permit a limited degree of searching in "cone" formation; and, by exposing vertically, to produce ahead of the hostile bomber a wall of light against which it may at some time be visible to fighters attacking from the rear, or to compel the hostile bomber, as it runs the gantlet of lights, to fly so close to one of the beams or group of beams that it becomes visible from the ground, thus enabling other lights to engage. In the parts of belts where the lights are more openly spaced, some beams act as pointers for the benefit of night fighters.

In gun-defended areas, some groups of searchlights produce the maximum degree of dazzle, by exposing (almost vertically) and dousing at fairly regular intervals, and even by waving about in the sky.

Other groups of searchlights possessing a "master" light cooperate with Flak. If illumination is obtained, the guns engage; if not, fire is sometimes directed at the point of intersection of the beam over the target area or just outside the bomb-release line, beams being held stationary until a suitable target presents itself.

(4) On clear moonlight nights.—This condition greatly reduces the efficiency of the searchlights. In target areas, tactics are adopted similar to those employed on a clear dark night, except that less attention is paid to dazzle. When attempted, this method has not been able to prevent crews from bombing accurately. In belts, tactics are similar to those employed on a clear dark night, except that a larger number of lights are detailed to indicate the course of hostile aircraft.

e. Dazzle and Glare

"Dazzle" is the blinding of persons in a plane caught in the direct light rays of one or more searchlights. "Glare" means obscuring the target from the plane crew by a light beam played between the plane and the target.

The extent of dazzle is dependent on the height of the plane, the number of searchlights concentrated on it, weather conditions, the direction of the light beams, and to some degree on the reactions of persons in the plane.

Dazzle or glare created by AA searchlights greatly lowers the ability of an aviator to adapt his eyes to seeing at night. Either dazzle or glare makes the location of targets difficult and lessens the accuracy of bombing. Also, keeping beams directly on a plane helps defending fighter-craft to approach the plane unobserved and to attack it more effectively.