perforce (adverb)
-necessarily

I was tired, so I perforce rested.

The word perforce can be defined by a few different terms. Perforce is an adverb that means unavoidably, by necessity or by force of circumstance and without choice.

No, perforce is not precisely correctly used in this sentence because the fire alarm is the subject of the sentence. The noise of the alarm might well indeed be unpleasant, but it alone would not require the evacuation of the building. As poor an option as not evacuating might be, it does remain an option. The alarm does not physically require an evacuation.

Shakespeare had only one son, Hamnet Shakespeare (1585-1596) who was perforce his eldest.