The Inter-Service Topographical Department

ISTD was a branch of Naval Intelligence that produced, among other things, detailed geographical and geological information for the use of planners in British and Allied headquarters and the commanders who executed their plans on the ground.4 The context of its creation was the impoverished state of British intelligence on the places where it was going to have to fight once Europe fell to the Nazis. It encompassed Naval Intelligence Division (NID)5 and NID6. NID5, formed early in 1940, employed teams of geographers in Oxford and Cambridge to produce detailed, long-range information on all aspects of locations where military operations were likely to take place. Among other things, this led to the production of the enormous, 58-volume-long Naval Intelligence Handbooks series, a feat that still ranks as one of the greatest achievements of academic geography. It took over SOG in October 1940, before, together with NID6, expanding to Manchester and beyond. By the time of the Normandy landings, NID6 employed 750 people.

NID6 began life in May 1940 with Colonel Bassett and the University College Oxford classics don Frederick Wells working out of a disused toilet at the Admiralty. Like NID5, it was formed when it was became evident that Britain lacked accurate intelligence about areas where its forces were operating, such as Norway, or likely to operate as the war developed. Campaigning in these areas was likely to involve hazardous amphibious operations featuring air, land, and maritime forces. NID6’s job was to produce topographical – or terrain - intelligence for strategic and tactical use when requested to do so by military planners. Though controlled by the Admiralty, it served all of the armed forces as well as Britain’s allies, coming to embrace officers and civilians not only from Britain but also from America, Holland, and Norway.

Much of ISTD’s work involved, in Bassett’s words, the study by experts of ‘how to get on a beach and get off it again’, a matter of critical importance for commando raids, the Dieppe Raid, the invasion of Madagascar, the mammoth Operation Torch landings in North Africa, the Operation Overlord landings in Normandy, and planned landings in occupied Malaya. This required the work of a host of specialists, in soil and sand, water tables, tides and currents, the weather, mining, engineering, and the built environment. Data was derived from a range of sources, including books and articles (in plentiful supply in Oxford), aerial photo reconnaissance flights from nearby Oxfordshire airbases, information provided by servicemen inserted into enemy-held territory by small boats launched from naval vessels (including submarines), photos and information provided by private companies with overseas interests, a contact registry of people known to have recent experience of living in or visiting overseas locations, and the ten million postcards and holiday snaps, sent by members of the public in answer to an appeal broadcast by the BBC, that came to form part of the Admiralty Photographic Library.

ISTD personnel working in Manchester College provided intelligence for the ‘Dambusters’ raid, working out the flow of feeder rivers and the maximum capacity of the water before overspill, a botany expert using the state of vegetation shown on aerial reconnaissance photos of the dam to assess when it was at its highest. ISTD also identified a suitable Scottish loch for practice runs. In another famous operation, ISTD provided intelligence for the strikes that eventually sank the German battleship Tirpitz (constructing a full-scale model of the fjord it was hiding in as part of its efforts to instruct the pilots who would conduct the attacks). ISTD was drawn upon by a diverse range of military ‘end users’: it helped direct commando raids, sabotage operations, and targeted air attacks; it identified terrain on which gliders might attempt safely to land, and onto which paratroops or supplies might be dropped; it identified areas where airfields might best be established, or where fresh water might be found; and it helped those planning the reconstruction of German oilfields on their capture.

The ISTD’s Fire Vulnerability Section produced hundreds of brightly coloured and information-laden maps, covering conurbations across the world where the Allies were likely to drop bombs or deploy land forces. It established which parts of cities were most susceptible to firebombs, targets where incendiary or ‘blockbuster’ bombs could be used to best effect (no point dropping a fire bomb on an area not likely to catch fire), and the fire vulnerability of buildings and infrastructure in the ports and inland towns and cities where Allied forces would mass as they invaded Europe and fought towards Berlin. This not only aided Allied targeting of towns and cities under enemy occupation, but provided valuable information once they had been captured – where for example, not to store ammunition in case of German bombing or shelling, where fresh water could be found, and where it might be safest to locate headquarters.