How satellite and aerial photography brings the war diaries to life
by Cynthia Gast
Most people, and especially the volunteers working on Operation War Diary, will recognize the names of the locations that played the biggest roles in World War I. Cities such as Ypres and Passchendaele along with regions such as the Somme were the sites of horrific fighting. Poperinghe was known to the soldiers as a place where they could have a break behind the lines, and the unfortunate mademoiselle from Armentieres is immortalized in song.
There are countless other towns, villages, farms, and forests that appear in the diaries. Each one is a place where the men of that unit fought, marched, or slept. To me, an important part of the story of the men on the Western Front is where they were. Where did they spend Christmas? What did they see in the villages behind the lines where they spent their rest periods? Where was that hill that caused so much trouble for the transport on a dark rainy night? I’ve spent a lot of hours searching for some of these locations.
The first step, even before filling in the Place tag, is to search for the name on Google Maps. I’ve learned that not all diary authors had a good grasp of the intricacies of spelling French place names and the search function in Google Maps helps with this problem by supplying several suggestions before I’ve even finished typing in the entire name.
Google Maps has a couple of other helpful features as well. I’ve learned that clicking on the town’s name on the map puts that name in the tab at the top of my browser. This is quite handy for spelling when I return to the diary page to type it into the Place tag. Another interesting detail is that while many of the very tiny hamlets are not labeled on the basic Google map, they do show up on the Google Earth view. An example of this that I came across recently involved the 1 st Division Trench Mortar Batteries. Their diary said they were in the village of Berthaucourt and I knew they were somewhere near Saint-Quentin. A search on Google Maps told me that Berthaucourt is now part of Pontru, but no matter how closely I zoomed in, there was no indication of its exact location. However, when I switched the view to Google Earth, I learned that it is just to the east of the crossroads that form the heart of Pontru.
As I’ve moved through the diaries, I’m less content with locating just the villages and towns mentioned by the author. These days, I’m digging deeper and looking for the farms and chateaus used as billets and bivouacs. I’m amazed at how many of the farms mentioned in the war diaries are still in existence today.
When I want to find a farm, I start on Google Maps, where search results are more likely to show me a road rather than the farm itself. However, when I zoom in on Google Earth view there’s often a cluster of farm buildings along that road. Sometimes I hunt using Google’s basic search function, which is particularly useful for chateaus.
Many World War I trench maps are now available online. Some sites offer sets for purchase but, along with IWM’s map collection, there are at least two sites that allow users to examine them at no charge. The National Library of Scotland and McMaster University in Canada both offer collections covering the areas where most of the fighting occurred. They both also offer information and links that cover how to read the maps, including the grid references. As an added plus, McMaster University also has a collection of aerial photographs of the Western Front.
Trench maps are fascinating. They reveal the complexity of the trench systems and show just how the features of the landscape fit into the systems. They also show the sometimes dark sense of humor possessed by the men who named the trenches. Whole sections of trenches are named for weapons, animals, or birds, as well as places back home, commanding officers, and the units occupying them. One system near Delville Wood featured trench names relating to beer, such as Pint Trench, Hop Alley, Ale Alley, Beer Trench, and Lager Lane.
Trench maps also often include farms, chateaus, villages, and anything else of importance to the men in that area, such as quarries and brickstacks. They also indicate the roads existing at the time the maps were drawn, many of which still exist today. When I want to find a farm or chateau, I compare the trench map with the modern map or Google Earth view using the roads as a guide. The National Library of Scotland also offers side-by-side and overlay features to help compare the old and present-day maps.
When I began as a volunteer at OWD, I had no idea of the things I would learn. The geography of the Western Front and how to read trench maps are just two of the amazing aspects of World War I that I now know. There are still many diaries to read and men to get to know through the official diaries they kept, and lots of spaces for more volunteers.
Recently, Steve Hirschorn at the National Archives has been looking at ways to visualise the information being generated by Operation War Diary Citizen Historians. As part of this work, he has taken maps found in the pages of the war diaries and, using the known coordinates of certain features contained within them, has fitted them to current satellite images using Google Earth. This process is known as georectifying and can help us assess how much the landscapes described in the war diaries have changed in the 100 years since they were written.
Over to Steve, who can tell you exactly how he’s done this…
Thanks to the efforts of volunteers using the #map hash-tag in the talk forum, it’s been easy for me to find georeference-able content. By geo-rectifying maps, it would be possible to use a GPS device to find the exact co-ordinates of anything that is documented in the maps, such as trench locations and routes, and machine gun emplacements.
Four KMZ (Google Earth/Google Maps) files are linked below. If you have Google Earth (free download available), you can use these files to view First World War maps overlaid on a recent satellite image. The KMZ files can also be imported into Google Maps, but the functionality via the website is more limited compared to the full Google Earth client.
After you have downloaded a KMZ file, you’ll see the war diary maps overlaid on the satellite view, but completely opaque. Look in the left-hand menu on Google Earth and by right-clicking an individual map item, you can select Properties and in the properties dialog box that appears, you can adjust the transparency from 0% to 100% and anywhere in between. I’ve tried to identify evidence in the current-day satellite images and street view photos of trench locations, but haven’t had much luck so far.
I’m amazed how well the most of the maps fit the current day landscape features. The odd road has disappeared here and there, but there are always enough reference points to fit the map, and they usually fit with just a bit of stretching and rotating, all of which functionality is also available in the free Google Earth client. A couple of them show trench locations (the map of Bullecourt) and machine gun placements (Ypres).
If you missed the link the first time, Google Earth can be downloaded here: http://www.google.co.uk/intl/en_uk/earth/
Steve’s map files can be downloaded using the following links:
- http://zooniverse-demo.s3.amazonaws.com/diaries_data/images/WO-95-1662-1_Bullecourt.kmz One of the better ones, a good fit to current-day road layout and showing the locations of trenches
- http://zooniverse-demo.s3.amazonaws.com/diaries_data/images/WO-95-1601-2_Ypres.kmz Another good fit, this time showing machine gun emplacements
- http://zooniverse-demo.s3.amazonaws.com/diaries_data/images/WO-95-1415-1_Hooge.kmz A map showing German trenches and the British Front Line
Lastly, as this is a new area of exploration for us here at Operation War Diary, and because none of us are experts on it, we have some questions which we hope you might be able to help us with:
- Is KMZ the best, most open format for sharing geo-rectified maps? Is there a better format?
- A bit of researching on the Internet suggests that there are ways of loading KMZ files onto a SatNav. Again, are KMZ files the best way of supporting this?
- Are there any web-based applications that enable geo-rectification of maps, and also provide a method of sharing geo-rectified maps?
- Do you have any geo-rectified maps you’ve created that you’d like to share?
- Are there any other ideas for things that we can do with the maps?
Post your answers in the comments here, or get involved on our forums at: http://talk.operationwardiary.org/#/boards
Tens of thousands of maps were produced by British forces during the first world war, from large-scale maps for senior commanders needing an overview of an entire front, to much more detailed topographical maps for front-line troops, which allowed them to accurately pinpoint enemy positions and establish the nature of the ground they held.
Many of these maps are preserved in the unit war diaries, with Citizen Historians uncovering more each day. One of the great benefits of tagging the war diaries is that it allows us to continue the mapping work carried out during the war itself, using modern techniques to establish a visual representation of the events of the time and the experiences of the units to whom the diaries belong
Image © IWM (Q 2306)
One way in which we can do this is to use place names, particularly those we can locate on the mapping tool contained within the Place tag, to site events geographically, which is a great way to quickly get an overview of a particular type of activity or event. The link below, for example, will take you to a map produced by Jim O’Donnell of the Zooniverse showing amalgamated unit casualty figures (tags showing 0 casualties have been discarded for this analysis), linked to geographic location and covering the years 1914-1918.
Bear in mind that this data set is derived from the first tranche of completed diaries – a little over 200 units in all. Imagine what the map will look like once we have completed all of the thousands still to be tagged!
Georectification is another exciting way in which mapping tools can add to our understanding of the content of the war diaries. This technique allows us to align first world war maps discovered in the diaries with modern satellite images of the same area. We’ll be doing another blog post soon to cover this and you’ll get to see some excellent examples of just what we can do – give yourself a head start by downloading Google Earth beforehand!