The invasion force had no artillery and was completely annihilated.

Answer: Option B

Reduced : make smaller or less in amount, degree, or size.
Destroyed : end the existence of (something) by damaging or attacking it.
Dismembered : (of a body) having had the limbs cut off.
Split : break or cause to break forcibly into parts, especially into halves or along the grain.
Annihilated : destroy utterly; obliterate.

Synonym of Annihilated is Destroyed