A Brief History of the Marque
Walter G.m.b.H. in Mühlhausen & Thüringen built motorcycles from 1903 to 1942.
Motorcycles produced prior to WWI were sold under the Möve marque which were fitted with Fafnir singles and twins.
The Möve was also produced by Walter in the late 1930s.
Jeane Herveu, one of the first women to race, rode a Walter with an OHV Buchet engine in the 1903 M.C.F. Concours in France. An example of this machine, possibly the same one, was part of the Guélon Collection.
There is also a Czech Walter marque built 1902~1949, see Walter of Prague.
A Walter sidecar was made in Germany - see the page on Sidecars
Notes1. Walter exported motorcycles under the Iduna brand according to peterzimmermann.de, but thus far no other record of Iduna has been found.
Sources: Wikipedia DE, German Resources, peterzimmermann.de
More information on Walter and Möve may be found in Deutsche Motorräder der Kaiserzeit 1885-1918 by Volker Bruse
Sun Dec 20 2009
Walter 1921 v-twin 750cc across the frame
mention on pages 57 and 105 on military motorcycle bug by David Ansell