Michael Dorosh kindly provided (for my old website on counterbattery) the following information from the Canadian Army Training Memorandum No. 24, March 1943, which came as a welcome piece of information to me, since I understood the theatre grid system of the Commonwealth armies, but had never even thought about how the Germans did it. Turns out they used a Stosslinie, thrust line (or point), drawn on a map. This is a variant of the offset method, in which a location is expressed by giving the distance to two edges of the map – except that the distance is given in relation to a randomly chosen line on the map.
The differences in locating units on the map were quite astounding to me, and I originally wondered why the Germans ever came up with such an unwieldy system. But I guess that in application it is not actually unwieldy, and it has the advantage to add to secrecy. While David Irving claims that Rommel invented this system to help his tanks advance in France, I simply doubt that this is true, since it appears to be a universally used system in the Wehrmacht.
The header carried by the document is preserved in this post. The Allied armies put out this kind of information to inform their soldiers about the capabilities of the German forces. The most famous of these may well be the manual to the 8,8cm AA gun published by the US Army. A lot of these information leaflets are published at the excellent Lone Sentry website.
NOT TO BE PUBLISHED The information contained in this document is not to be communicated, either directly or indirectly, to the Press or to any person not holding an official position in His Majesty’s Service. **
THE GERMAN MAP REFERENCE
1. The Germans have a map reference system which they call “stosslinie”, which means “thrust point.” A line is drawn on a map. Theoretically, it may run in any direction, but in practice it is found to run either in the direction of the German intended advance or down the axis of a reconnaissance unit.
2. The line begins at a fixed point and continues indefinitely in the required directions. For convenience it is usually divided into centimeters. To give a map reference, a perpendicular is dropped from the reference point to the thrust line. Measurements are then given from the starting point of the line to the point where the perpendicular cuts the thrust line; then along the perpendicular to the reference point. Since the point may lie on either side of the thrust line, the second figure has to be prefaced by either right or left as one looks toward the enemy.
3. A typical reference would be 12 right 3.5. The figures always are centimeters; therefore, the actual distance on the ground represented by each unit will NOT always be the same but will vary according to the scale of the map.
4. In order to make the code more secure, the following variations may occur:
1. The scale may start with an arbitrary figure; that is, the starting point may be called sixty instead of zero; so that our map reference would read 72 right 3.5.
2. Dummy figures are often used. By previous arrangement, it is agreed that the first, third and fifth figure of any map reference will be dummies. The above map reference, for instance, might be given as 87329 right 83359.
3. Finally when more than one thrust line is being used, perhaps by a Corps or Army, they are numbered and map references begin with the number of the thrust line.
5. Instruments have been found that consists of a rule in translucent material graduated in millimeters, with a shorter ruler similarly graduated, fixed at right angles which slides up and down on the larger ruler.
6. Operators with practice can give references very quickly.
The US Army also issued an explanation of the system to its soldiers.
Excerpt from chapter 14 of “Artillery in the Desert”, Military Intelligence Service, Special Series No. 6, November 1942:
One of the most interesting methods of enabling map references to be sent in the clear with security is the “thrust line” method used by the Germans. (This method is similar to the code described in FM 18-5, “Organization and Tactics of Tank Destroyer Units,” June 16, 1942, paragraph 231 b (2) (e).) It consists of a line drawn upon a map which theoretically may run in any direction but which actually usually extends in the proposed direction of advance or down the axis of a reconnaissance unit.
The line, which begins at a fixed point and continues indefinitely in the required direction, is usually divided into centimeters for convenience. To give a map reference, a perpendicular is dropped from the reference point to the thrust line. Measurements are then taken from the point of origin to the point where the perpendicular cuts the thrust line, then along the perpendicular to the reference point. Since the point may lie on either side of the thrust line, the second figure must be prefaced by either “right” or “left”, as one looks toward the enemy.
A typical reference would be “6 right 3.” (See fig. 15.) The figures are always in centimeters; therefore, the actual distance on the ground will vary with the scale of the map used. The scale may start with an arbitrary figure, and have dummy figures interspersed, or it may start with the number of the thrust line when there are several in a given area. These devices make the code difficult to break rapidly.
Thrust Point – From http://www.lonesentry.com
Figure 15.–The “thrust line”
Instruments have been found consisting of a transparent ruler graduated in millimeters, with a shorter ruler similarly graduated and fixed to slide up and down at right angles to the longer ruler. Practiced operators can give references very quickly.
The whole document is worth reading, by the way.
Here is an example order fixing a thrust line, which I found in the files of 21st Panzer Division.
Order from Panzergruppe Afrika fixing a Thrust Line. Rommelsriposte.com Collection
Secret Command Affair
German Africa Corps CP, the 16 November 41
Operations Section 17 copies
No. 1274/41 secret Command Affair 12th Copy
Re: Thrust Line
For the map Libya 1:400,000, German “preliminary special issue I 1941” (Leaf Bardia), the following thrust line is ordered:
A = 0 = Gr. el Arid (near Trigh Enver Bel, 50km west of Bardia)
B = 15.8 = Gr. el Abd (14km south of Sidi Omar)
For the German Africa Corps
The Chief of the General Staff
The use of a temporary, operation-dependent system is very different from the Commonwealth system, which used a permanent ‘theatre’ grid superimposed on a map of the area of operations, or even wider. The UK National Archives website explains it quite well at this link. This system had originally developed in World War I (World War I was to the artillery what the French revolution was to politics), and the development during the war to end all wars is very well charted at this link. Locations on the map would be expressed through two numbers with identical but variable length. The longer the number, the more precise the location information. Information on this can be found on Nigel Evan’s site at this link. This system, or one like it, is now universally used by the western armies at least.
Practice in North Africa
In North Africa, the thrust line was determined by Panzergruppe HQ during CRUSADER, and my guess is that this did not change when the HQ was upgraded to army status. I believe that in other theatres thrust lines were determined by Corps HQs (a Panzergruppe was equal in status to a Corps HQ), but I am not certain about this. During CRUSADER I have come across two changes of Panzergruppe’s thrust line, but there may have been more. There is also a good discussion on the system at this link.
So, in the German system, a unit would report something like this, and the note below explains it:
Following executed relief CAM* assembled, with Ariete in area around 48.5 left 4.5, with Trieste around 48.5 left 5.5. CP CAM from 17 January 10h00 48.5 left 5.
The shows a Stosslinie on an Italian map used by the German intelligence officer in Panzergruppe Africa’s command staff. The line starts with the value of 65 north of B. el Harmarin/south-east of Mechili, and ends with the value of 105 at Bir el Gobi. Rommelsriposte.com Collection
*Corpo Armata di Manovra (Mobile Army Corps, not Mobile Armoured Corps as one reads sometimes!), the later XX Corps in the Italian army, consisting of the Ariete armoured and Trieste motorised divisions and the RECAM reconnaissance detachment.
**Since His Majesty is dead, I guess I have been released from that obligation….
The “Stossline” system is very similar to the one UK and other artillery observers use for correcting fire – pick an arbitrary but relevant line (most often the line from the observer to the target), then give corrections based on length along that line, and distance left or right of it. I believe this is discussed in detail at Nigel Evans’ site, however it may be worth noting that this system was *not* in use during WWII. Blackburn (Guns of Normandy, I think, or either of the others from the trilogy) talks about the Cardinal Point system used then, which is a simplified method that only uses N, S, E, or W. While simpler conceptually, and much better than what came before it, cardinal point is actually harder to use in practice. I wonder if the germans used the Stossline for artillery adjustemnts?
Erm. Anyway. The fundamentals of the Stossline system are quite simple and common. The tricky bit, looking at them retrospectively, is that you must know the start point and orientation for any given stossline for subsequent references to make sense, although I suppose that it can be inferred to a certain degree from context and any references to specific locations. However, when reporting up, or across, command chains the reporter would need to ensure that the reportee had the necessary information.
Another thing that occurs to me is that it doesn’t seem particularly accurate. The example above of the order defining a stossline is a case in point. Different units would, in all likelihood, plot slightly different locations for points A and B, giving slightly different orinentations of the Stossline. While this wouldn’t matter too much at distances close in to point A, the further out you went the greater the variation would be. Similarly transferring the Stossline from the ordered sheet to other sheets at different scales would introduce differences and inaccuracies. Then again, when you’re talking about the location of divisions, I suppose an error of a couple of hundred metres isn’t too important.
The final thing that occurs to me is that the Stossline system would be of supreme usefulness in unmapped, or poorly mapped areas, but perhaps less useful in well mapped areas. Russia and North Africa are the obvious candidates for useful locations here. I wonder how much the system was used in, say France 1940, or in any of the campaigns of 1944-45.
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Well David Irving claims it was invented by Rommel for use in France… Anyway… There is some info on this in the discusison of the AHF I linked. But it is not quite clear to me what they used at what point in time for which purpose.
I had a few more thoughts about this system:
I find it odd that they just used cms (ie, map-scale independant), rather than actual kms. As a side note, this also makes it trickier to ‘read’ the references without reference to the relevant map, since I – for example – had always assumed the references to be in kms, thus forming a sort of mental map of movements which I now realise is largely incorrect, or at least wildly out of scale. Similarly, as a commander receiving instructions via a series of stossline points I’d have to plot them to make sense of them, whereas being given map grids it’s possible to make sense of the distances involved merely by inspecting the numbers. On the otherhand, making map overlays would be a lot easier with Stosslines.
Another thing (and this ties in to the previous point): when reporting, you’d need to ensure that point the person giving the report and the one receiving it had the origin, orientation, AND the correct map, since the distances only make sense on that map (or, rather, at the scale that map is at).
The secrecy inherent in this code stikes me as fairly fragile, especially if a single line were used for more than a couple of days (and it appears that they could be used for weeks at a time, given the right circumstances). Over time it would be fairly easy for friendly intelligence services to use a variety of sources to ‘decipher’ any fudge factors introduced to obfuscate locations.
I wonder at what level stossline were routinely used. Obviously DAK and PAA used them to order their divisions and independent assets around. Presumably divisions used them to order their regiments and other assets about the place. But would dattalions use them to order their companies and platoons around? I suspect not, as I don’t think the system would be accurate enough for the fine level of detail required at that level, but I have no evidence whatsoever to support that.
BTW, my comments in this and the previous post shouldn’t be taken as me saying the system is stupid. On the contrary; I think it’s rather clever. I do wonder just how it worked in detail, but the German Army was nothing if not professional, so I’m pretty confident they had it all worked out, even if those details remain obscure.
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Rommel claimed to have invented the Thrust Line for the Germans, and Patton claimed to have invented it for the Americans. Its origin was probably some unknown junior officer, but his superiors liked it and used it until it came to Rommel’s attention and he claimed it as his own.
The Thrust Line works for the Germans because, unlike the British, they did not have gridded maps. Their maps were similar to road maps with large coordinate points marked on the edge and large scale (1:100 000 or 1:300 000). British grid maps were 1 inch=1 mile (1:63 360), IIRC, and the Ordnance Corps went great lengths to find data to draw their maps.
To: jonsowden; re: artillery adjustment : The simplest system which the observer can use is the line Observer-Target, and I think that all artillery used this. The Cardinal point system mentioned in “The Guns of Normandy” may have been imposed due to fire support from the navy. The CP system would simplify the plotting for the moving vessel and speed response, and, since naval gunfire might be used on any target, all targets were corrected that way.
From what I’ve seen it is quite possible he invented (or at least was the first to use it) it while in France in 1940. We’ll never know I guess. The absence of a grid system is indeed correct, and makes it more difficult to trace actions on a map. It also presented an issue for aerial strike navigation I should think.
All the best
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The translation of “Blatt Bardia” is a bit unfortunate in my book, since “Leaf” is describing foliage from trees or bushes. Single papers are “sheets” but I might also be wrong since I’m no native speaker…
Ah good point! Will amend that.