Building the Project Overlord missions means collecting huge amounts of historical information to populate the virtual battlefields and picking realistic objectives.

While there’s quite a lot of detailed information online and available for free, the type of information we need is often not available in the necessary detail.

To build a convincingly accurate representation of the Normandy battlefield, we need to know which units were in which locations on a given date.

Sometimes, online unit diaries such as the one for 21 Base Defence Sector RAF give us this information…

… but in many cases the information simply isn’t available in this kind of detail.

What we do is place units on the map in their original locations as recorded in wartime diaries. Like this radio mast on the banks of the River Seine observed by Allied aircraft during June 1944.

What to do when the information isn’t available? Go out and find it, of course!

The Project Overlord research archive contains about 120 Royal Air Force Operational Record Books (ORBs) downloaded from the National Archives.

It also contains links to tens of websites run by historians and memorial societies that contain details of bomber raids. One excellent example that we draw on heavily is the 416th (Light) Bombardment Group website, which contains full navigation plans for each and every one of the 416th’s A-20 Boston raids.

The original route plan for Mission 94 of 8th July, as flown by the 416th BG.

The National Archives in Kew, west London, contain the original records of thousands of British wartime military units, as well as original intelligence reports. But many of these haven’t been digitised.

What better way to find the information we need to build more PO missions than to go out and get the original historical information straight from the original documents?

TNA holds thousands upon thousands of unique documents, many of which relate to the RAF’s Second Tactical Air Force (2TAF) and the air war over Normandy. Above is an original British flak map from 24th July 1944, showing the locations of light, medium and heavy flak concentrations. This comes from TNA file AIR 24/1543.

Among the most valuable documents in TNA for Project Overlord’s purposes, except for the flak maps, are the 2TAF daily intelligence summaries.

These are the collated observations of every US and British air squadron, together with details of which squadrons flew where, what they bombed and where and when they met German aircraft and fought them.

Above is an excerpt from the 2TAF daily intelligence summary from 10th June 1944, giving the exact grid references of locations bombed and strafed by some RAF P-51 Mustang squadrons.

The coordinates given can be turned into modern map references through the Echo Delta coordinate converter. They can also be located by cross-referencing against the actual map used by RAF and USAAF pilots during the Normandy campaign.

From two visits to TNA this year, PO has about a thousand hi-res photos of original 2TAF intelligence summaries from June, July and August 1944. We are very slowly turning these into standalone PDF documents.

Here is a sample: 2TAF Intelligence Summary No.195 for 1st August 1944. PDF, 2.24MB.

We hope you enjoy flying on Project Overlord and appreciating one of the most accurate publicly-playable digital representations of the Normandy air war in 1944. Enjoy!