Learn Turkish: Yangın yüzünden binayı tahliye etmeye mecbur kaldık. - We were forced to evacuate the building due to the fire.

The phrase mecbur kalmak (to be forced/compelled) requires the Dative case on the action you are forced to do. To attach the Dative case to a verb, we first turn the verb into a short verbal noun using -mA (making it etme). Then, we add the Dative buffer and suffix -(y)e, resulting in etmeye (literally 'to the evacuating').

Could we say mecbur olduk instead of mecbur kaldık in this sentence?

Yes, but mecbur kaldık feels more natural here. While mecbur olmak simply means 'to be obliged', mecbur kalmak (literally 'to remain obliged') implies being left with no other choice due to a sudden, unfolding situation. Since a fire forces a sudden reaction, kaldık captures that sense of situational compulsion perfectly.

Why is it binayı (with the Accusative case) rather than just bina?

The word bina is the specific direct object of the compound verb tahliye etmek (to evacuate). Even though etmek is in a verbal noun form (etmeye), it still governs its object just like a regular verb. Since 'the building' is a specific, known object, it takes the Accusative case suffix -(y)ı, giving us binayı.

We used yangın yüzünden for 'due to the fire'. Could we use instead?