Polish Forces

Some artillery unit

http://nowahistoria.interia.pl/historia-na-fotografii/ostatnie-chwile-przed-wybuchem-ii-wojny-swiatowej-zdjecie,iId,1550768,iAId,124398#1551633

According to my source, it’s the last moment before the war and somewhere near the Gdańsk frontier. The guns look to me like AA.