The reference website for coordinate systems
during World War II is Thierry Arsicaud’s website
: Notes on the “Modified
British System” used on the European Theatre of Operations during the
1919, Great Britain adopted in its territory the “British System”,
based on a Cassini-type map projection and the use of a
grid designed to facilitate the reading of the coordinates of the designated
points . This system was replaced
1927 by the “ British Modified System”, more
suited to cover large geographical areas and military operational use by
land or airlift
“British Modified” system was used during the second world war
by the British and American armies by being
to European, North African, the Near East and South East Asian operation
The following figure , from
Thierry Arsicaud’s website shows
the areas corresponding to the projections in course
World War II.
The South Italy projection is a secant Lambert
projection ( only one standard parallel), which
uses the ellipsoid Bessel 1847.
The South Italy projection
management with ArcGIS
You will not find this projection in those available
standard with ArcGis.
the projection is created, it will be necessary to enter the
transformation methods to the usual systems (WGS84, NTF, RGF93).
The parameters of the South Italy projection are the
39 , 5 ° N
In terms of the geodesic system, the parameters
Name: Bessel 1841
on the following link to download a file .
prj with all the necessary definitions.
To move this projection to
the data block or to
a GIS layer, open the coordinate systems definition window
and click on the import button:
How to set up
transformations in ArcMap
The transformation of Bessel datum 1841 to NTF or RGF93 is
done through a three- parameter
transformation dX , dY, dZ .
The values to go from Bessel to NTF are :
dX = 850,
dY = -143 and
dZ = 160
The values to change from Bessel to RGF93 or WGS84 are :
dX = 682,
dY = -203 and
dZ = 480
To set up the transformation of this geodesic system towards the
one you usually use :
1-Open a new project in ArcMap
a layer in the usual projection
system (Lambert 93 or Lambert I , II, II, IV , or extended II )
a map in South Italy projection
You will notice that a window
appears, indicating you that the geodetic systems are different and
which proposes you to set up a transformation.
4-Click the Transformations button If you are working with Lambert I, II, II, IV or II extended
sure that in Convertlater you
in To , you have well
8- In Name type Bessel_NTF
settings enter the values 850, -143 and 160
for, respectively, X, Y, Z.
OK , and OK
Next time you have to perform a transformation, you
will find this transformation in the drop
The management of the South Italy
projection with QGis
Similarly as with QGis, the transformations are
(provided that you inform the ellipsoids ), it
much simpler to manage this projection than with
To define a new coordinate system
, click the Preferences menu ->CustomProjection…
In Name enter
In settings enter
the proj4 definition of the projection:
+ proj =
lat_0 = 39.5 + lat_1 = 39.5 + lon_0 = 14 + k_0 = 0.99906 + x_0 = 700000 + y_0 =
units = m + no_defs
now you can work with the South Italy projection
and overlay data in this
projection with data depicting other projections.
Thank you so much for the precious information. I was wondering which are the parameters to set the transformation up from WGS84 to Bessel.
Thank you so much.