This is the 7070th most frequent Polish word.
hitlerem
"Hitlerem" is the instrumental case of "Hitler," referring to Adolf Hitler in Polish.
Here, 'Hitlerem' is used in its instrumental case to denote the means or context through or by which an event is associated, in this case with Hitler.
W szkole nauczyciel wspominał o okresie rządów Hitlerem.
At school, the teacher spoke about the period of Hitler's rule.
In this sentence, 'Hitlerem' is again in its instrumental case to express the tool or association within the narration related to Hitler.
Film dokumentalny był nakręcony i opowiedziany Hitlerem.
The documentary film was made and narrated related to Hitler.
Here, 'Hitlerem' is in the instrumental case showing comparison ('with Hitler').