Barrage Maps and Planning

[JohnC]

Looking at some late war barrage maps, it strikes me that there must have been a huge amount of work involved to plan them. To estimate the infantry’s anticipated rate of advance, plan the lifts, plot and print the maps and then at unit level trace them for use, without calculators or computers, is an astounding achievement. And that’s without considering the logistics of getting the guns in place and fed with ammo.

My questions are:

1. How far in advance of zero hour did this planning have to start? Say for a barrage like the assault on Le Quesnoy, attached. Given the pace of allied advance during the 100 days, it can surely only have been a few days. It’s not something I’ve ever seen referenced in unit war diaries.

2. Given that facilities existed to print master copies of barrage maps, why were they then traced by hand? Just this process must have taken hours per copy. What was the point?

 

[ianjonesncl]

On 13/12/2022 at 13:31, JohnC said:

How far in advance of zero hour did this planning have to start?

It would vary from months to days depending upon the situation. The initial Artillery Orders for the battle of Messines were issued in April 1917 for an operation that began on 7th June. The attack on Le Quesnoy I looked up to be 4th November. Do you have a sate for the IV Corps Artillery Instruction 287 from which the baggage trace come ?

On 13/12/2022 at 13:31, JohnC said:

. Given that facilities existed to print master copies of barrage maps, why were they then traced by hand? Just this process must have taken hours per copy. What was the point?

I suspect the traces would be used to calculate the base firing data. 

The base firing data needs to be calculated from a map to measure the bearing and distance from the gun position to the target. Doing the plot on an actual map with all the various symbols the small pencil point of the target gets lost, so the best mechanism is to plot the target on a 'blank' map, ie a squared piece of paper. This was the concept behind the introduction of Artillery Firing Boards in 1916. 

The initial trace would have been drawn on top of a normal map in order to establish key features and boundaries. Thereafter the barrage lines could be drawn. You would now have a mechanism whereby you can calculate the base firing data with accuracy.

I am not sure that the printing mechanisms at the time would be able to take a piece of tracing paper able able to print copies. There is also the problem with multiple copies that the accuracy could be lost. In more modern times the traces that were supplied which had been printed had distortions between copies. No problem if they are used to provide a battle picture, but would be problematical if they were used for any activity that required accuracy, artillery targeting being one. 

[JohnC]

Thanks for that explanation Ian. The artillery instruction was issued on 1st November, initially without maps, and zero hour was 05:30 on 4th.

The war diary of RA IV Corps has a third type of map, a red overprint on a monochrome topographic map, attached. I can see from the messy appearance of this map why a blank map showing just the barrage data would have been useful for the gunners. So do I understand that the purpose of the hand traced version was to avoid inaccuracies introduced by the field printing process?

[JohnC]

The version in the war diary, from TNA.

[ianjonesncl]

On 14/12/2022 at 20:50, JohnC said:

So do I understand that the purpose of the hand traced version was to avoid inaccuracies introduced by the field printing process?

I have no specific reference to it being the purpose. 

The thoughts are based upon the experience of the manual calculation of firing data and the fact that tracing paper was still being used at least to the late 1990's for the safety traces.