Panzer column advancing through Western Belgium,May 1940.Lower right corner,German motorcycle(photographer?)Greetz,brummbar

Panzer column

Panzer III Ausf. A im Gelände

This appears to be an early German tank destroyer improvisation, consisting of a PAK 35/36 37mm antitank gun, crudely mounted on a Krupp Kfz 81 light truck (? Netherlands, 1940).  If so, it prefigured a long posterity of field modifications combining later PAK and (usually) armoured carriers and half-tracks.  Some divisional engineering shops made a bit of a speciality of such conversions.  Best regards, JR.