invade

verb

1. march aggressively into another's territory by military force for the purposes of conquest and occupation"Hitler invaded Poland on September 1, 1939"
2. to intrude upon, infringe, encroach on, violate"This new colleague invades my territory"
3. occupy in large numbers or live on a host"the Kudzu plant infests much of the South and is spreading to the North"
4. penetrate or assault, in a harmful or injurious way"The cancer had invaded her lungs"