In March 1945, the commanding officer of 23rd Antiaircraft Artillery Group, Colonel J.B. Fraser, wrote an update to his report about Detecting Ground Targets by Radar. The text that follows replicates, verbatim, the text of this memorandum. The only changes made either fill out abbreviations, update punctuation, or split large paragraphs into smaller ones. Brief explanations shelter within brackets.
General
Three radar sets, SCR 584, have been in operation on a corps front for more than six weeks. Two were emplaced on prepared platforms behind Maginot Line forts while the third moved into and out of position under cover of darkness.
Difficulties
Some difficulty has been experienced with the condensation of moisture in the pedestal and elevator assembly caused by raising and lowering the pedestal in and out of the warm van during cold weather. Other breakdowns were due to failures in the M-7 generator. Heavy rain and snow greatly reduced operating ranges. A strong wind which caused vegetation to sway violently made successful operation almost impossible, especially if the vegetation was wet. A heavy shower of Window [chaff] dropped by friendly bombers interfered with operations for about two hours one night.
Sensing for Registration
Using two sets, no difficulty was encountered in plotting the strike of each round from a 155mm howitzer and bringing the center of the impact on the target. This method was equally successful when POZIT ammunition [fitted with variable time fuzes] was being used.
Unilateral registration - using one radar - has been fairly successful for plotting in range only, as long as the angle gun-target-target-radar is between 600 and 1,200 mils [34 to 68 degrees]. In unilateral registration, when visibility permits, it has been found better to sense the deflection visually, spotting the bursts through the telescope mounted on the parabola. If the initial bursts are more than 40 mils [2 degrees] off in deflection, firing a round of white phosphorus facilitates correction.
Results Obtained
One set located south of Sarreguemines [a city in eastern France] averaged ten detections per night. Their locations were telephoned to the S-2 of the infantry regiment and artillery fires laid on the more promising ones.
On one occasion, a definite change in the type of enemy activity was detected. In an area where detections normally had been mostly personnel, the responses changed one night to indicate a large number of vehicle movements. Twenty-one vehicles were reported and fired upon. The following night, detected enemy movement was again primarily of personnel.
After friendly infantry established a bridgehead, their advance was plotted and phone to the regimental S-2.
In response to an infantry request that a suspected counterattack be located, the radar picked up an estimated three hundred troops in an area. Artillery fire was placed on the area and the counterattack did not develop.
One of the sets emplaced behind a Maginot Line fort was used for spotting friendly shell bursts. The echoes of the shells were seen on the range scopes for a considerable distance before they burst. On one occasion, when the target was defiladed from the ‘radar line of sight’, the shell bursts provided enough of an upward shower of metal and dirt to be ranged on.
Source
‘Immediate Report Number 71 (Combat Observations), 9 March 1945’ Immediate Reports of Combat Observations 130 to 1 Combined Arms Research Library
For Further Reading
When I was stationed in Europe- an LRRP- we used GSR to vector us in and out of different areas along the old Cold War Border. I guess GSR owes its legacy to Col Fraser. That was a great post- I had no idea. Serves to show we have lost and forgotten more history than we know. Thank you for surfing the archives. The historical context and lessons are important to remember.
The Radar Units By coming as men in full with their tools come as allies, not vassals or despised augmentees.