An advance into enemy territory, an attempted invasion; an encroachment, an incursion.
Often followed by in, into, or on: initial progress made toward accomplishing a goal or solving a problem.
To attack; to infringe; to encroach on; to violate.
To move into.
To enter by force in order to conquer.
To infest or overrun.
To make an unwelcome or uninvited visit or appearance, usually with an intent to cause trouble or some other unpleasant situation.