Edit August 2018: Since this post has recently received some exposure on Twitter, I will add that you can find a high-resolution scan of the map at the AGS Library in Milwaukee, here. The map is dated 29 December, 1943, and is OSS Map 2920.
As part of their mapping efforts, the OSS produced this jaw-dropping “OSS Theater Map” at the height of World War II. It’s notable for a number of reasons.
You immediately notice the unusual projection of the world. According to the designers the map is a
“Lambert’s conformal conic projection at a scale of 1:1,500,000 with standard parallels at 20 degrees and 60 degrees. The map is so designed that any number of sheets may be mounted together to form a theater of any size. To accomplish this, the projection was modified in three areas along the Equator.”
In other words, as the inset shows in the bottom left, this map blends together four projections into one. Where they touch, the Equator is a straight line. Furthermore, being a conformal map it shows “any small area in its true shape except those areas of land masses in the bands near the Equator.”
Second, the OSS has derived a scheme for systematizing the entire globe into a coherent grid, as shown in this detail:
Each one of these grid units (eg 1743 for the British Isles in the detail above) was produced as a separate base map, without thematic information. So if you want a map to cover the British Isles, you sent for Map #1743. If you wanted an expanded area, you could join it to map #1619 (“Amsterdam”) to the East where it would fit alongside. The 1 G showed it was map in the first grid to the west of the Prime Meridian, in the G-band north of the Equator. (Unfortunately this meant some duplication of grid/band numbers; so for example “Abidjan” and “Lagos” were both 1 A. However, they had different map numbers: 1672 and 1501).
Here’s an example of one of these grids, #1513 (Brunei). This is dated 1942.
Detail of header showing the date and that it was given to the AGS at the end of the war:
Here’s a detail of the map content showing the area around Brunei:
It appears to show not only hydrography, but also some basic elevation detail, as well as railroads, political divisions and of course places names (in English).
The other notable aspect of the map is this comment at the bottom, which raises a somewhat controversial and sad reflection on the AGS:
The AGS thus discarded all the individual maps that make up this series, much to their shame. The Brunei one shown above is the only one left in their archives. (Why Brunei?)
(These maps are just a sampling of the hundreds of maps I’ve looked at over the past 2 months thanks to a generous Fellowship from the History of Cartography project in Madison and Milwaukee, Wisconsin.)