What would a member of the Hitler Youth have seen during the invasion of Poland in 1939?
What did they do? what types of things did they see? I'm trying to write a story based on a member of the Hitler Youth during that time.
You might be better off writing about the experience of a German or Polish soldier or that of a young Polish person or family during the invasion of Poland, as the Hitler Youth were never in Poland. Those who did see military action of any kind did so mostly on the Western Front and in Berlin later in the war.
If you were a German soldier, you would have witnessed some pretty fierce combat. You would have seen long columns of Polish refugees retreating from the fighting. You would have seen Polish horse cavalry charging against German tanks being massacred. You would have seen entire villages and cities leveled by bombing and on fire. German planes would be constantly overhead. You might run across the tens of thousands of Polish soldiers who had been captured, being held in barbed wire camps. The sound of gunfire, artillery and bombs could be heard most days.
The most disturbing thing would be the large numbers of soldiers and civilians who would be dead along roadways and in the rubble of cities. It would happen so regularly that you might not notice anymore.
If you want to write this from the view of a young Polish person, then you would have been more likely to be seeing the Polish and German armies going by in one direction or the other, and you might be on the run yourself trying to get away from the danger.
If you do just want to write about the Hitler Youth, I would change the topic from Poland to something else like witnessing the Nazi Party rallies or marches in your city, to the bombing campaigns against Germany, or the arrest of Jews in your city.