an act or instance of invading or entering as an enemy, esp. by an army.

the entrance or advent of anything troublesome or harmful, as disease.

entrance as if to take possession or overrun

the annual invasion of the resort by tourists.

infringement by intrusion.

noun

retreat , surrender , withdrawal

noun

aggression , assault , breach , entrenchment , foray , forced entrance , incursion , infiltration , infraction , infringement , inroad , intrusion , irruption , maraud , offense , offensive , onslaught , overstepping , raid , transgression , trespass , usurpation , violation , attach , encroachment , influx , intrenchment