While going through photos, I came across this map from the Muzeum Uzbrojenia in Poznan showing the movement of the Polish army (shown in red) through central Poland when the Nazis invaded in September 1939 :

It’s a little hard for me to read, but I believe Poland had a stronghold in the Kutno region and for a few days they held back the Nazis (shown in blue).
This region is exactly where my family came from. My great grandmother was born in Żychlin and eventually settled with her husband and children in Włocławek. They would have been long gone when the war started, but some of my grandmother’s siblings were still living in Włocławek. Here’s another layer of memory I need to integrate into my family story. How profoundly destabilizing it must have been for them to watch as the Polish forces fell and they became foreigners in their own country.