This is the 4109th most frequent Polish word.
batalionu
"Battalion."
Here, 'batalionu' is in the genitive case to indicate belonging or association with the battalion.
Ten żołnierz był częścią batalionu stacjonującego w górach.
That soldier was part of the battalion stationed in the mountains.
In this sentence, 'batalionu' is in the genitive case to denote possession, as the commander is of the battalion.
Dowódca batalionu wydawał rozkazy żołnierzom na polu bitwy.
The commander of the battalion was issuing orders to the soldiers on the battlefield.
Here, 'batalionu' also appears in the genitive case, showing the relationship between the map and the battalion's position.