What is "invasionary"

Usage examples of "invasionary".

For all we know it was an invasionary beach-head which left us because it was met with forces which it estimated presaged resistance on a scale which would prove too expensive.

Moon reacted to the news of an invasionary force with admirable calm, Trini thought.

Altis, who told the boy he would indeed grow to become a warrior of legends, that he would lead an invasionary force such as had not been seen on the face of the earth for many generations.