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Remembered Today:

Understanding French trench maps and their references


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Dear colleagues - 

I am studying the French Sixth Army for the period September 1916. I have their Official History and War Diaries (‘JMO’s’).

However, I am having difficulties aligning map references in their War Diaries with the relevant French maps and hope someone can help me.

An example may help to explain: - the map I’m using is the Plan Directeur, Combles, 26.9.1916 (1/10,000).

The War Diary is that of the 12th Division (part of 6th Corps, in 6th Army), no. 26 N 290/2. An entry on 20th September mentions creating a support line, ’marked by 771 – 2228 – 2133.’

The French diaries normally define positions or lines by these ‘points’ (which I have read were originally artillery target positions). Be that as it may, the Combles map is dotted with various points but of the three points 771 – 2228 – 2133, only 771 appears on said map. So, looking at the war diaries and this map, I have no idea where this line goes!

There are lots of examples of this sort of thing – points (ie positions) mentioned in war diaries but not shown on maps.

I have looked up as many maps I can find in the French sources, to no avail, but of course may have missed something.

Can anyone advise on how to identify positions or lines, mentioned in the text but (apparently) not shown on the relevant map. (The British grid reference system seems much more logical!)

Thanks in advance - Bill


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13 hours ago, Biltea said:

only 771 appears on said map

Where is this located (nearest village or preferably an extract posted as an image)?  There are a few maps with 771 or 0771 in the general area of Combles, so let's narrow it down.

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771 is just south of Bois Labe Farm, which is itself just south of Bouchavesnes - Bill

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No problem - that's why it's always good to post what you already know.  It's eye-wateringly difficult to read some of these numbers and in the end I gave up and thought I'd await your response.

TrenchMapper has Nord de la Somme, 1:20,000 Edition: 14/09/1916 Secret. Trenches corrected to 14/09/1916. Printed 14/09/1916 mapid: wfa_000032..

I've aligned 771 at the top left and it is just south of Bois Labe Farm.  Follow the trench southwards from 771 past 2331 and you'll see 2228 east of the t in Thierry.  The way they have written 2 is consistent over the entire map (they've almost looped the top of the 2 to resemble a 9).  Now follow the line south and SE of the letter y in Thierry is 2225, then 21nn.  I'm taking an uneducated guess that this is your 2133.

Extending the map down to Feuillaucourt, I can see a few 20nn, 21nn and 22nn series but this to me is the only obvious candidate (which does not make it the correct one).

Cheers, Bill



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Well done Bill, you beat me to it.


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Hi Bill/WhiteStar Line

Thanks for your helpful reply. I confess I should have spotted 2228 on the map, but didn't, so thanks for pointing it out. As for point 2133, it may well be c,lose to points 2122, 2123 and 2124 as you think likely, but being a nit-picker I was hoping for something  a wee bit more accurate. Am I likely to find another map with point 2133 on it?

On a slightly different subject, it seem like a crazy map system to define positions by map points alone. I would have thought the French would have used a grid system, ie using eastings and northings. A separate topic recently indicated that the Frenh Lambert system used eastings and northings. (I am not a maths expert!)

Any thoughts how I could use the Lambert system - or any other -  to identify point 2133 please ? (I have dozens more like 2133t that I am looking for!)

Thanks again - Bill


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If we assume the 771 target is the road junction, then the Lambert coordinate from wfa_000032 as shown in TrenchMapper would be 42.22, 553.30.

Right click, choose Map ID jump and use the ID that Bill gave, wfa_000032. Pan in small amount to prevent the map changing.

Lambert coordinates should be Easting, Northing.


Ferme Bois Labe2.jpg

Ferme Bois Labe.jpg

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