From 'mailplane' to 'fighter'.
It's interesting that it's well known the Dornier Do 17 was promoted as a fast mailplane cum airliner initially, as a cover, but here Dornier are clearly aiming a bit higher with it as a 'fighter'. (Ironically the Do 217 was to become quite an efficient
night fighter.) And an advert in a British trade journal too, one that the Dorniers would soon be trying to Blitz.
From the online flight archive:
http://www.flightglobal.com/pdfarchive/index.html