Invasion
Part of speech: noun
Definition: A military action consisting of armed forces of one geopolitical entity entering territory controlled by another such entity, generally with the objective of conquering territory or altering the established government.
Example sentence: An invasion of armies can be resisted, but not an idea whose time has come.
Encroachment
Part of speech: noun
Definition: An entry into a place or area that was previously uncommon; an advance beyond former borders; intrusion; incursion.An intrusion upon another's possessions or rights; infringement.That which is gained by such unlawful intrusion.An unlawful diminution of the possessions of another.