Yesterday I was poking around eBay looking for things I just can’t live without when I stumbled on an auction that caught my eye. One of my canned eBay search criteria – ‘aerial mapping’ – triggered a hit for an auction for a US Air Force publication on something called Project Casey Jones. The subtitle was the real attention getter: ‘Post-Hostilities Aerial Mapping; Iceland, Europe, North Africa, June 1945 – December 1946′. I was intrigued but the eBay seller was asking far (far) too much for the document. But since this was an official USAF publication I figured there was a good chance it was already available on-line in digital format. A quick Google search turned up a the document in PDF format on an on-line library and I grabbed a copy.
As I started to read the report it dawned on me that I never really knew where the base mapping imagery came from that allowed the Army Map Service to re-map all of western Europe and North Africa quickly and accurately right after the close of WWII. I just assumed the aerial photo missions were done on a piecemeal as-needed basis by US assets or we collaborated with host countries like France or Italy to obtain civilian aerial photo coverage.
As it turns out the collection of aerial mapping imagery at the close of WWII was a far more centralized and directed effort than I could have imagined. The fact that the project was carried out so quickly, comprehensively and effectively is remarkable and is one of the great untold stories in the US Army’s topographic history.
In 1944 it was clear to senior Allied leadership that Germany’s days were numbered and thinking started to turn to projects that would help secure the US position in post-war Europe. A huge issue that had emerged from both the ground and air campaigns in Europe was the lack of accurate and up-to-date maps and air charts. During the war the Allies’ mapping services, like the US Army Map Service, scrambled to meet the demand for large and medium scale maps. They often relied on outdated local maps of dubious accuracy, supplemented where possible by photo mosaics or photomaps based on aerial photography taken by reconnaissance aircraft. The science of mapping using stereo aerial mapping photography was well understood at the time, and the US Army Air Force (USAAF) had the necessary cameras and aircraft at their disposal, but flying long, slow and precise flight lines over enemy held territory was out of the question while both sides were still shooting at each other.
Allied military leadership realized that once the shooting stopped there would be a very short window of opportunity during which they would be able to fly photomapping coverage of most of western Europe. The idea was to get the job done while the American’s still had the political clout and the resources in Europe. The US Government and the USAAF applied a carrot and stick approach to the problem. In concert with the British Royal Air Force, the USAAF would fly the conquered territories (Germany, Austria, Italy, etc.) at will (“we won, you lost, tough luck”), and the Allied, newly liberated or neutral nations (France, Spain, Switzerland, Netherlands, Belgium, etc.) would be offered a copy of all aerial imagery collected over their territories (“we’re your friends and we’re just helping you get back on your feet”). In the end it worked, and over two million square miles of new stereo aerial imagery was collected in about 18 months.
The Project Casey Jones report brings to light some very interesting historical tidbits. The first were the technical issues. How do you keep a big, heavy bomber like a B-17 on a straight, steady course for hundreds of miles? The answer turned out to be ingenious. After the pilots failed multiple early attempts to keep the aircraft flying straight and level the job was turned over to the bombadiers and their Norden bomb sights. Since the Norden bomb sight effectively took control of the aircraft once the bombing run to the release point was initiated – controlling aircraft attitude, direction of flight and compensating for wind drift and other factors – it became a relatively simple matter to re-program the sight so that visual check points along the photographic flight line became the ‘release points’, and the bombardier actually controlled the flight by flying from check point to check point along the flightline path using the Norden. Simple but effective.
Norden bomb sight in the nose of a B-17. From this station the bombardier took control of the aircraft and flew from check point to check point along the flightline. Many of the flightlines were 200 or more miles long
The other interesting factor was quality control. The USAAF was flying to meet US Army Corps of Engineer (Army Map Service) requirements and had to adhere to mapping imagery standards for image overlap, side lap, aircraft attitude, cloud cover, haze and other factors. In the beginning the rejection rate of aerial imagery was unacceptably high – some flight crews only hitting the mark 20% of the time. Part of the problem was a lack of familiarity with the mission, part was mechanical problems with the installation of the mapping camera systems, and part was weather and atmospheric conditions. To help solve the problems and improve the success rate for the photo missions the Corps of Engineers put photomapping officers and technicians in each of the squadrons. These personnel would grab the film as soon as the aircraft landed, develop it and quickly review it while the flight crews were still in the area. They could do a quick post mortem on the success or failure of the flight and provide the crews with valuable feedback on what was needed on upcoming missions. As air crew experience increased the success rate increased, and towards the end of 1946 the success rates for each mission hovered around 60%.
Other factors worked against the project; weather during one of the worst winters in modern memory (1945 – 46), high personnel turn-over rates caused by rapid demobilization and political issues that delayed or canceled overflight permission. But in the end the USAAF was successful, and Project Casey Jones was effectively complete by September 1946.
So what became of the two million square miles of mapping photography flown during Project Casey Jones? It was immediately transferred to the the Army Map Service and was used as a primary cartographic data source for at least the next 20 years. It was used in the wide-scale production of up-to-date tactical and operational scale maps of western Europe by American and British military mapping agencies, maps that supported the operational backbone of NATO well into the 1960’s and perhaps beyond.