Inter-Services Topographical Department (ISTD), Oxford

AddressHarris Manchester College, University of Oxford, Mansfield Road, Oxford, Oxfordshire OX1 3TD, UK
Location typeHeadquarters Site
AccessPublic Access
Site Ownership and Access InformationThe Ashmolean Museum can be visited by the public. Other locations are at various Oxford colleges, which are generally not publicly accessible.
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The ISTD played a vital but sometimes overlooked role in the planning of D-Day.

Before a site could be selected for Allied troops to land on D-Day, a huge amount of information from a range of sources had to be gathered and analysed. For several years before D-Day, this work was done by an organisation called the Inter-Services Topographical Department (ISTD), based in Oxford colleges. Its staff comprised both civilians and armed forces personnel. It was established at Manchester College, Oxford, but also used other buildings such as the Ashmolean Museum. A vast amount of information had to be collated. Many civilian experts were consulted, for example about the geology of the French coast (covering not just the features of the beaches, but also other subjects such as the water supply). Allied photo reconnaissance aircraft flew along the coast, both at very low level and from a high altitude. Reports from the French Resistance on the construction of German defences added vital details. Even closer investigations were performed by members of COPPs (Combined Operations Pilotage Parties), who made stealthy landings in the middle of the night to assess the beaches under the noses of the German sentries. Much of this work covered a much wider area than just Normandy, to help preserve the secret of where D-Day would take place.

In 1942, ISTD made an appeal on BBC radio for postcards and photographs that British people might still have from pre-war holidays on the continent. In the first post, 30,000 letters were received, and in the end over ten million photographs were sent in – a big task to analyse!

As well as gathering information, the ISTD also produced various booklets that were used by the Allied forces on D-Day. One example is the ‘concertina-style’ beach silhouette books, which were a series of connected photographs showing the Normandy beaches. These were used by landing craft crews to help them identify landmarks, so that they could ensure they delivered the troops on board to the correct location.

View on the D-Day On Your Doorstep map