Artificial Moonlight, WWII Tactical and Technical Trends, No. 57, April 1945 (Lone Sentry)

Allied troops in France and Italy are making effective use of "artificial moonlight," produced by antiaircraft searchlights, for night operations and movements.

The term "artificial moonlight" has been coined to distinguish searchlight illumination from normal moonlight, which is referred to as "movement light" in night operations.

Considerable future development may be expected in the tactical use of mobile searchlights to assist ground operations during darkness. Artificial moonlight introduces a wide field for ingenuity, since a fairly wide variation of lighting effects is possible to suit particular requirements in almost any weather.

British reports indicate success in the use of searchlights to illuminate battlefields in Italy. Indirect lighting facilitated the movement of tanks, infantry, and motor transport, as well as other activities that required a degree of illumination at night.

On the Gothic Line in Italy the searchlights were sited 5,000 to 8,000 yards behind the front lines and usually near the top of reverse slopes. A battery of 24 lights had a maximum frontage of 5,000 yards. Sixteen lights covered 3,000 to 4,000 yards and eight lights 1,000 to 1,200 yards. However, these frontage figures do not include a much larger area in which movement was aided by diffusion of the light.

British searchlights also were used on several occasions in France, in some cases closer to the front lines than in Italy. Instances have been reported where the lights were placed 4,000 to 6,000 yards behind the front line, in defilade, and adjusted on low clouds to give reflected light equal to that of a half-moon.

In France the use of artificial moonlight simplified and expedited removal of minefields at night, made blackout driving easier, and aided in detecting and defeating German patrols. In addition, engineers were able to make emergency road repairs in forward areas at night. Since the Germans faced the searchlights, the light did not aid them as much as the Allied troops, who had their back to the source of light. Furthermore, even in diffused light, a considerable shadow effect was produced on the far side of hedges, tanks, and houses. From the concealment of these shadows Allied troops could observe German troops and installations, which were thrown into relief.

German Reactions

German prisoners of war who have faced Allied artificial moonlight differed widely in their opinions of its advantages and disadvantages. The Germans reasoned that the Allies had introduced the use of artificial moonlight to direct artillery fire and naval gunfire; to illuminate target areas; to show Allied aircraft the location of friendly troops; and to help Allied infantry pick out German defenses.

The Germans claimed that the searchlight illumination aided their sentries and outposts in detecting the approach of Allied infantrymen; that withdrawing movements were aided, especially in bad weather; and that would-be deserters were deterred by fear of being detected by their own troops.

Although few Germans admitted finding artificial moonlight a serious handicap, there was one fairly general statement among the many conflicting ones: that artificial moonlight has a definite nuisance value. The majority of German troops felt decidedly uneasy during the period of illumination, not only because of the uncanny atmosphere, but also because they felt that they were now handicapped even during what used to be their one period of free movement.

The German viewpoint was that the advances of Allied infantry were made easier by artificial movement light, not only because the attackers were able to see where they were going, but also because the shadows offered concealment and were so "unnatural" as to deceive the defenders.