If I thought that getting historical background to Cordon Sanitaire defoliation efforts (see previous post) was challenging, I was wrong!

Trying to find anyone who has in-depth information on the electronic early warning systems installed on the fences was an even more daunting task. To be very honest I am not in any way convinced that what I have managed to find holds too much water and this is once again where I will be hoping that someone, somewhere reads this post, tells me I have written complete rubbish and puts things right. I can take it and no offence will be taken I assure you. We simply need to get this as factual as we can. There has to be Rhodesian Army veterans that actually installed and monitored the electronic side of things that can help here.

The following redaction comes from more than one source, the reliability of which has not been confirmed to me. From an intelligence source and reliability perspective I therefore have no option but to rate it as F/6 (Insufficient information to evaluate reliability. May or may not be reliable/The validity of the information cannot be determined) and should therefore by no means be quoted as being the way things actually were. Read on………..

For the sake of simplicity we will consider the Cordon to be 25 metres wide, fenced on both sides, and containing anti-personnel blast mines.

On the home side a system of electronic sensors divided into monitored sectors and wired to sector control boxes formed the basis of the early warning system. I have not been able to find any information as to what type of sensors (movement, vibration, broken electrical circuit, audio, etc.) were used, nor who was responsible for installing them (possibly the Rhodesian Corps of Signals (8 Signal Squadron)).  According to one source these control boxes were placed in bunkers close to the home side fence and manned full-time by troops waiting for an alarm to be set off.

Logic makes me think that a combination of activation triggers may have been used. Apparently the idea was that any penetration of the Cordon would be detected by detonations or some form of electronic sensor. My information claims that reaction to these events was primarily by vehicle and took place within 10 minutes of a signal being received. In addition to the vehicular response, artillery fire was also used to put down fire on ranged, pre-selected targets. I imagine this would be from 25 pounder howitzers or possibly 120mm mortars.

It is my understanding that the only parts of Cordon Sanitaire to be fitted with an electronic early warning system were the Musengezi/Mukumbura, and Nyamapanda to Ruenya minefield. Soon after these areas were completed a significant amount of false alarms were being recorded. This resulted in finding no enemy presence at the alarm trigger point. Due to the significant cost of ammunition being expended on these false-positive events, it was decided to curtail the rapid response on these areas in 1975. An ongoing Cordon Sanitaire review shelved the whole idea of an early warning system shortly thereafter.

And so ended the Cordon Sanitaire early warning system.

I do not know how effective these measures were as I never encountered them during my time serving in the Rhodesian Corps of Engineers. Personally I do not think the electronic system was as successful as the planners initially thought it would be and with the Rhodesian economy heavily burdened by sanctions and an ever-increasing defence budget there was little chance of any project surviving unless it showed significant success indicators (body count, infiltration mitigation, etc.).

I located the following on the issafrica.org website.  They seem to confirm in some ways parts of the foregoing:


I will continue to seek further sources to help unravel this interesting and little known subject.

Please also have a look at my website dedicated to Rhodesian and South African Military Engineers.  Please join us on the forums by using the following link:



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