Some army units were decimated during the surprise attack.

Answer: Option D

Denounced : publicly declare to be wrong or evil.
Captured : take into one's possession or control by force.
Defeated : having been beaten in a battle or other contest.
Destroyed : end the existence of (something) by damaging or attacking it.
Decimated : kill, destroy, or remove a large proportion of.

Synonym of Decimated is Destroyed