The German 280-mm railway gun of the "Bruno" series en route to the front, during the invasion of Poland; 1939. 
The 280-mm  (28-cm) schwere Bruno Kanone (E - Eisenbahnlafette (railroad mounting)), was a German railroad gun used during World War II in the invasion of France and Poland. 

280-mm railway gun

German 37-mm ZSU Sd.Kfz.7 / 2 is preparing for battle at the corner of Budennovsk Avenue and st. Turgenevskaya in the city of Rostov-on-Don. November 1941. 

Rostov-on-Don captured

German gunners with a camouflaged 3.7 cm PaK 35/36 anti-tank gun in combat position in a village, covering the incoming road.