Searchlights became the third level of American Air Defense in World War I and were a significant factor in U.S. anti-aircraft artillery (AAA) successes of the Great War. By the outbreak of World War II, they were integral to coast defense and, as the ground forces gained mobility, so too did the searchlight units fielded by the American army.
The standard searchlights in service during WW II were Sperry and General Electric 60-inch carbon arc 800-million candlepower lights. More on how they worked can be found here (link to come).
Searchlight battalions were usually teamed with AAA gun battalions, since the two systems worked exceptionally well together against nighttime air attack.
In the late 1930s, target acquisition by searchlight relied on huge sound locators to detect the engine noise of an incoming aircraft. These were simply large funnels focused toward the sky that an operator would strap into and listen for the drone of propellers for hours on end. However, with the adoption of radar, the searchlight battery now had a far more precise method of acquiring and tracking a target with significant increase in the time between initial acquisition and visual confirmation.
This interval would allow searchlight units to bring their lights on target without switching them on. Once a targeted aircraft was within range, the light operators would simply turn their lights on, blinding the enemy pilot and signaling the guns to commence firing.
At the outset of the war, three radar sets were available to the US Army, the SCR-268, SCR-270, and SCR-271. The SCR-270 was a portable radar and was made famous on December 7, 1941 when the SCR-270 at Opana Point, Hawaii detected the Japanese air armada headed to Pearl Harbor less than an hour before the attack began. The SCR-271 was similar to the SCR-270, but was a fixed-position radar. Of the three, only the SCR-268 was specifically designed as a gun- or searchlight-laying radar.
Searchlight units also were tasked with coordinating with friendly Night Fighter units in-theater. In August 1944, while providing searchlight defense for the port of Cherbourg, B Battery of the 225th AAA Searchlight Battalion was attached directly to the 442nd Night Fighter Squadron in order to assist with both nighttime interception of German attack aircraft and successful guidance of friendly P-61 Night Fighters back to base.
By the end of World War II, 87 AAA searchlight battalions had been fielded, serving defending U.S. and Allied positions in all theaters of war.
Like their gun battalion brethren, AAA searchlight battalions had a significant amount of support equipment needed to maintain operational capability. A multitude of trucks, trailers, and generators were all integral to the searchlight battery’s operations.
Prior to the introduction of gun-laying radars in 1942, as alluded to above, the primary method of acquiring incoming airborne targets was by acoustic location. Sound locators like the M2 could detect approaching aircraft and bring both guns and searchlights to bear with surprising effectiveness, but were obsolete by the beginning of WW II.
The searchlight control station was operated by three men and was used to aim searchlight by hard-wired remote control. One operator would maintain visual contact with the target and adjust the searchlight’s aim, while the other two would keep the control station on azimuth by adjusting hand wheels. The control station was placed several hundred feet away from a searchlight so that the controllers could see the illuminated aircraft.
The SCR-268 radar was the Army’s first gun-laying radar system. It has been designed to work in concert with both heavy guns and searchlights. As the newer SCR-584 gun radar came into use, SCR-268 radars continued to serve with AAA searchlight battalions and performed admirably in the searchlight direction role.
With the lessons learned from World War I and the advances in gun and searchlight directors, the U.S. entered World War II having developed some of the most advanced antiaircraft techniques in the world. With the addition of new radar acquisition and tracking, searchlight battalions would have the azimuth and range to their targets almost instantly, requiring them simply to turn on their lights once enemy aircraft were in range so that the gunnery sections of the AAA team could bring the enemy airplane down.
Get down to Skylighters basics …
Check out some searchlight imagery …
Get the bigger picture about AAA in The Hammer of Hell: The Coming of Age of Antiaircraft Artillery in World War II …