Dutch military motorcycle squad with Schwarzlose machine guns.
Eysink supplied these machines to the Dutch army prior to the First World War, in 1913.
The same machines continued in army service until the German invasion. The machine gun mounted on the motorcycles is a Schwarzloze, and was fired usually only when the machine was stationary, the advantage being that the weapon could be transported quickly to the required location.
Source unknown
Eysink Motorcycles