Answer: invasion

AnswerCrossword Clue
INVASIONEncroachment
INVASIONMilitary incursion
INVASIONRaid
INVASION"War of the Worlds" event
invasionthe entrance or advent of anything troublesome or harmful, as disease
invasionentrance as if to take possession or overrun
invasionthe act of invading (to enter by military force)
invasionact or instance of invading or entering as an enemy, esp. by an army
invasioninfringement by intrusion