His helmet looks as if it is a leftover from 1918?

Several armies were wearing that helmet in 1939 from Hungary to China. The Polish motorized troops wore it, while the cavalry wore adrian style helmets and everyone else wore the unique Polish helmet. It was a sign of an elite status like those leather coats? Lots of countries wore all kinds of WW1 leftover helmets, even the US, UK and France (with slight changes in straps and liners)

Thanks for the information. Something new learned! In combat, this might have given some confusion, though!

Black Brigade is the nickname bestowed by the German Heer onto the Polish 10th Motorised Cavalry Brigade who they so labelled on account of the Black leather jackets that all of the officers, NCO's and motorcycle troops wore in the Brigade. When you combine a mid thigh length leather jacket with knee high black boots and black berets, and in the case of the Motorcycle troops oversized black gloves its easy to see where the nomenclature came from. (http://brushesandbayonets.blogspot.com/2017/08/flames-of-war-black-brigade-1-command.html)

once more: great info!!!