When I started writing my History columns here on Chicago Boyz, one of my objectives was to explore the “military historical narratives” around General Douglas MacArthur, so I could write with a better understanding about the “cancelled by atomic bomb” November 1945 invasion of Japan. But in doing so for this column, the strangest experiences are doing deep, original, historical research. Trying to follow a trail of research on something you think you know — in this case trailing the classified “Need to know” Radar hunting “Section 22” in 6th Army Administrative Orders — and then going down Alice’s rabbit hole and finding a “Detailed Reality” about something completely different. The “completely different” in this case being a provisional parachute supply company created in February 1944 that used the Rebecca & Eureka, a “Retro-high tech” VHF (AKA Television bandwidth) Radar Interrogator-Beacon System — a distant technological ancestor to the civilian “secondary radar” transponders used for air traffic control on today’s wide body passenger jets.
The Rebecca and Eureka radar beacon system represent something of a “Keystone military technology” By that I mean an analogy to the biological concept of a “Keystone species” in an ecosystem, not unlike the role of algae in the ocean ecosystem or grass for a prairie ecosystem. Rebecca and Eureka radar beacons are the “Keystone technology” for a wide range of ‘unconventional’ operations including clandestine supply, intelligence & pathfinder operations ranging from planting a few agents to the support operations for an airborne army. or large naval landing.
Rebecca and Eureka was WIDELY used by the British Special Operation Executive (SOE) and American Office of Strategic Services (OSS) in N.W. Europe, Italy, Yugoslavia, and Burma. This beacon system was also used by American airborne pathfinder operations at Normandy plus Operations Dragoon, Market-Garden and Varsity. And now, its use is documented with this 6th Army Parachute Supply Company in the South West Pacific to support air drops to 6th Army Reconnaissance assets and possibly with both the Allied Intelligence Bureau agents and Filipino guerrillas.
Figure 1 – Rebecca & Eureka radar beacon system diagram with both aircraft and ground elements shown. Photo Source: https://wrotetrips.wordpress.com/2015/06/04/a-salute-to-the-troop-carrier/The Duxford Radio Society, of the Imperial War Museum, Duxford, England, describes the Rebecca & Eureka radar beacon (shown Fig 1 above) as follows:
A VHF (Secondary) Radar Interrogator-Beacon System
Rebecca & Eureka formed a system of portable ground-based beacons and airborne direction finding equipment initially designed to assist the air-drop delivery of supplies to the Allied Armies and Resistance groups in occupied Europe.
Rebecca was the airborne station, and Eureka was the ground based beacon
The ground based beacon consisted of a super-regenerative receiver and transmitter, originally operating in the frequency range 214 – 234 MHz**, powered from a battery via a vibrator power supply unit. A portable tripod mounted aerial was erected when communications was required.
[**This Rebecca & Eureka bandwidth covers upper Channel 12 and and lower channel 13 in American Television.
See “Retro-High Technology Background Notes” at the end of the column.]
As I have written previously:
“One of the maddening things about researching General Douglas MacArthur’s fighting style in WW2 was the way he created, used and discarded military institutions, both logistical and intelligence, in the course of his South West Pacific Area (SWPA) operations. Institutions that had little wartime publicity and have no direct organizational descendent to tell their stories in the modern American military.”
Today’s column identifies another of those many “throw away” logistical institutions, adding to a long list including –
o MacArthur’s 7th Fleet Guerrilla Support Group — 7th Fleet Guerrilla Resupply Task Group 70.4
o MacArthur’s Human Porter Logistics — The combination of C-47 Radio navigation air drops with neolithic human porters to destroy Japanese air power in 1943 at the Wewak airdrome in New Guinea
o MacArthur’s Mission X — The Transportation Corps Small Boat Section coastal shipping that supplied MacArthur forces from Buna New Guinea in 1942 to the Occupation of Japan in 1946.
o MacArthur’s “Red Bull Dust Express” — The African American truck convoys that resupplied Darwin, North West Territories, Australia in 1942 after Japanese carrier air strikes and air power in East Timor cut off coastal shipping for a year.
That MacArthur’s South West Pacific Area (SWPA) theater would be interested in this technology as a logistical solution to night/bad weather air drops to special forces or other conventional pathfinder operations can be surmised by this passage from my “MacArthur’s Human Porter Logistics” quoting General George Kenney’s book “The MacArthur I Know.” from pages 71 and 72:
Over at Port Moresby the transport pilots worked out a scheme of dropping supplies in bundles of 300 pounds, each with a parachute attached; this method could be used in bad weather. Flying on instruments, just as if he were in a fog, the pilot flew toward the airdrome radio station, using his radio compass for direction. When the plane passed directly over the radio station, the needle of the compass flipped and at that moment the pilot signaled the man in the rear of the airplane to shove the bundle with its attached parachute out the door. The plane would then circle and keep repeating the performance until the whole cargo had been delivered. I had watched a test during which sixteen bundles had been dropped from an altitude of 2,500 feet, while the pilot was flying hooded and entirely by instrument. The bundles had all fallen inside a circle one hundred yards in diameter.
This delivery tactic was used to resupply the 32nd Division troops at Buna in 1943 and saved the invasion after three days of bad weather cut off food resupply. Once this tactic was available, it was later used by Kenney for his most famous deception operation of the war, The destruction of Japanese air power at Wewak.
And the existence of the Parachute Air Supply Company can be inferred from the Pacific Warfare Board Report No. 23 Operation of Ground Reconnaissance Troops. 9 July 1945. In it, there are reports from the following units of their Reconnaissance work in Luzon which mention resupply behind Japanese lines:
32d Infantry Division, Cavalry Reconnaissance Troop
43d Infantry Division, Cavalry Reconnaissance Troop
43d Infantry Division, 103d Infantry Regiment, Intelligence & Reconnaissance Platoon
43d Infantry Division, 169th Infantry Regiment, Intelligence & Reconnaissance Platoon
43d Infantry Division, 172d Infantry Regiment, Intelligence & Reconnaissance Platoon
According to one college professor I have corresponded with on matters relating to Filipino guerrillas, “submarine resupply-only” of such units is the current historical narrative. As the locations these units were working were far from coasts, air resupply was the only real option, an option without documentation. (There is a reason for those standard narratives.)
Sometimes You Get Lucky
Yet for all of that, I was not looking for this parachute air supply company. I was looking for clues of Section 22. By complete accident, I ran across the following document from the US Army’s Combined Arms Research Library – Digital Library:
Headquarters Sixth Army Amendment No.1 to Administrative Order 14 to accompany Field Order 25 — Part_2
This letter “Ltr HQ. Alamo Force, AG 58 Q-6, sub:, “Standing Operating procedure for Air Supply, 14 Feb 44.”, is in the above document.
The letter described a special operating procedure (SOP) for 6th Army the provisional air resupply company [Troop D, 16th Quarter Master Cavalry Squadron (Provisional Air-Sup. Co.)] created eight months prior to the Leyte campaign that seems to be the air supply node for several types of 6th Army recon units above and perhaps the Allied Intelligence Bureau Philippine Regional Section operations with Filipino guerrillas. The SOP is page 132 (49 of 65 as it is the 2nd of two parts) thru 137.
Wrapping up with a Possible Section 22 Connection
MacArthur’s theater didn’t allow in the OSS, but its radar hunting/ELINT Section 22 had radar liaison officers with the following —
1. China Burma India (C-B-I)/South East Asia Command (SEAC),
2. Washington DC,
3. London as well as
4. Both 5th and 13th Air Forces.
Any radio countermeasures related Rebecca/Eureka lessons learned would have flowed via the Section 22 liaison route to the GHQ SWPA. They were on top of the ‘need to know’ subject matter expert list for all radar related classified documents transmitted across theaters to the SWPA.
So ends another Pacific History column, where a search for one extinct SWPA intelligence organization turns up another extinct logistics organization and changes our understanding of General Douglas MacArthur’s WW2 fighting style.
Retro-High Techology Background Notes
“High Tech” even WW2’s “Retro-High Tech” like Rebecca/Eureka can be “scary” to the ‘non-nerd’ for all the math based technology terms like bandwidth, frequency, pulse repetition frequency, etc.
Television is a useful tool in explaining/communicating about “Retro-High Technology” to a general audience, because the WW2 era used modern Television bandwidths for radar tools. Check out this link — http://en.wikipedia.org/wiki/Television_channel_frequencies
Using the information there, see that:
1. The American SCR-270 early warning radar was at 110 Megacycles (AKA Megahertz) This places it mid way between Channel 6 and Channel 7 in US television terms, in VHF band II.
2. The American SCR-268 search light radar was at 205 Mhz. That places it at channel 12 in US Television terms like Rebecca & Eureka .
3. The SCR-270 radar, the SCR-268 radar and Rebecca/Eureka are “Meter Band” (2.7 for the SCR-270 and 1.5 meter for both the SCR-268 and the beacon system respectively), in the TV “VHF” band.
Here is another example of relating WW2 “Retro-High Tech” Radar to ubiquitous home technology
Frequency limits in megahertz (Mhz).
Less than 225 Mhz — Meter band radar — US TV channels 13 and lower to commercial radio
225-390 Mhz – P band — Meter to Decimeter Radar – Between US TV channels 13 and 14
390-1550 Mhz – L Band — Decimeter Radar — Below TV Channels 14 to 83(+) & Cellphones
1550-5200 Mhz – S Band — Microwave radar 10 cm — microwave oven or police radar guns
5200. 11000 Mhz – X Band — Microwave radar 3 cm — microwave oven or police radar guns
11000-33000 Mhz – K band — Microwave Radar 1 cm — microwave oven or police radar guns
Sources and Notes:
1. Burton, Chris, “The Eureka-Rebecca compromises: another look at special operations security during World War II.” Air Power History, Dec 22, 2005
2. D-Day and the Wizard War
Posted on June 5, 2014 by The National Air and Space Museum
3. Duxford Radio Society, Imperial War Museum, Duxford, England
Equipment History Files 16-01-2011
A Brief History of Rebecca & Eureka
4. George C. Kenney, The MacArthur I Know, Copyright, 1951,DUELL, SLOAN AND PEARCE, New York, Library of Congress Catalog Card No. 51-10404
5. “Ltr HQ. Alamo Force, AG 58 Q-6, sub: “Standing Operating procedure for Air Supply, 14 Feb 44,” found in “Headquarters Sixth Army Amendment No.1 to Administrative Order 14 to accompany Field Order 25,” page 132 (49 of 65 as it is the 2nd of a two part Adobe PDF document) thru 13
6. Pacific Warfare Board Report No. 23 Operation of Ground Reconnaissance Troops. 9 July 1945, National Archive Research Agency, MD II Archives
7. Rebecca/Eureka transponding radar
In testing, Eureka II proved to be too heavy for practical use, so A.C. Cossor was selected to build a Mk. III version. They used US miniature 9000-series tubes for this version and used a much smaller battery with a three hour life. This version sparked US interest, who started production of a number of versions of the Mk. III as the AN/PPN-1 (Eureka), AN/PPN-2 (Portable Eureka) and AN/TPN-1 (Transportable Eureka). The AN/APN-2 (Rebecca), also known as the SCR-729, used a display that saw use for a number of purposes.
8. The working of Rebecca-Eureka radar device for dropping bombs over blind targets.
A training film ‘Blind Bombing’ depicts Rebecca-Eureka radar device being used for low level bombing over blind targets. A bomber aircraft in flight at a low altitude over the forest. The OSS (Office of Strategic Services) officers look at the plane. Animation depicts the Eureka agent guides the Bomber aircraft in flight. The OSS men carry at the field. A hand of OSS ground agent encircles the enemy objective in his area. Bomber aircraft in flight over the objective area. A parachutist jumps in the target area. Animation shows the ground agent helping the Eureka agent to enter the target area. A part being selected for setting up Eureka beacon. A man hold Eureka, a radar beacon in his hand. U.S. Army Air Forces A-20G Havoc fighter aircraft in flight. The Rebecca operator in a cockpit. The Rebecca operator reads an indication. The aircraft in flight from where the beacon can give signal. OSS officers looks
at the enemy location on a map. A parachutist boards the aircraft. The aircraft in flight. The ground agents look at the enemy target. The parachutist jumps at the target area. The agents runs and help him to gear off and they leave the field. They look into a paper. Both of them read the bombing table and set the Eureka location according to it. The Eureka being set up and tested. The ground agent activate the Eureka. The pilot and Rebecca operator get in the aircraft . Pilot at controls. The aircraft in flight. The beacon contact being made. The operator looks from the oscilloscope and signals back to Eureka. The aircraft in flight over the beacon. Animation describes the oscilloscope pattern and aircraft in flight according to the beacon position. Aircraft in flight and Rebecca operator sends the alert signal. The ground member in contact with the Rebecca. The operator picks up the bomb release and in action. The ground agent gives signal and the bomb being drooped. Animation depicts the bomb being dropped at the right position
This historic stock footage available in HD and SD video. View pricing below video player.