This is the 14562nd most frequent Russian word.
патрульным
"Patrol officer" or "patroller."
In this sentence, 'патрульным' is in the dative case, referring to the patrol officers as the indirect object.
Патрульным удалось быстро задержать нарушителя.
The patrol officers managed to quickly apprehend the violator.
Here, 'патрульным' is in the instrumental case, indicating the means by which the action was performed — meeting.
Мы встретились с патрульным около главного входа.
We met with the patrol officer near the main entrance.
In this instance, 'патрульных' is in the prepositional case (plural), defining the entity responsible within the context of time (night).