Near  Łowicz/Poland, September 1939. Damaged Polish armored train No. 11 "Danuta" captured by German forces. 
(Bundesarchiv Bild B 206 Bild-GD-52)

Captured Polish armored train

Polish Home Army soldiers draw a bead from behind what looks like a barricade composed of bedroom furniture, Warsaw Uprising, 1944.

The weaponry here is interesting.  The soldier on the left is using a Mauser 98K, presumably captured from the Germans at a reasonably recent time.  The man to the right, however, is using a a somewhat more unusual weapon - a Browning Automatic Rifle of, essentially the 1918 design (BAR M1918).  This was, depending on how one views it, an early light support machine gun, or alternatively the Daddy of all assault rifles.

The BAR M1918 was originally intended as a "trench sweeper" for specialist American units in WW1 (the US equivalent of German "stormtroops", more or less) but was found to be unsuitable due to its weight and relatively unweildly profile.  It went on to have a varied career, involving the production of several variants.

The BAR variant shown here is almost certainly adapted for Polish Army requirements, the main modification being recalibration to use Mauser-type 7.92 mm ammunition.  This variant - the Browning wz. 1928 - was originally manufactured by the ever-adaptable Belgian arms industry on behalf of Poland under license; subsequently, it was manufactured under licence in Poland.  In the following years, this weapon became the main light support automatic weapon for the Polish forces.  Presumably the weapon shown here was one of the many thousands in the arsenals of the Polish Army at the beginning of WW2.

With my limited horizons, I have only seen one BAR M1918, so the speak, in the flesh.  This was, when I saw it, displayed in the Belgian Musee de l'Armee in Brussels, in the WW1 section.  It was an "original" US model, held in the arms of a mannequin displaying American uniform of 1918.  A notable (and particularly American) feature of this weapon was the fixation over the top of the breach block of a nicely engraved little plaque (clearly attached while the rifle was being finished) asserting the patent of the Browning/Winchester corporation and stating the patent number and date.  Not, perhaps, the most relevant matter for the user, as he stood ankle-deep in muck somewhere in northern France but, well, you never know where intellectual property law is going to catch up with you ... Best regards, JR.

Polish Home Army - Warsaw, 1944.

This picture was taken in Hrubieszów, on the 14th of July 1935 during inspection of the regiment by its commanding officer, colonel Romuald Niementowski. At the front major Henryk Dobrzański.