onrush,
onset,
onslaught,
attack a forceful forward rush or flow; "from the bow she stared at the mesmerising onrush of the sea where it split and foamed"; "the explosion interrupted the wild onrush of her thoughts"
interpenetration mutual penetration; diffusion of each through the other
invasion the act of invading; the act of an army that invades for conquest or plunder
infiltration a process in which individuals (or small groups) penetrate an area (especially the military penetration of enemy positions without detection)
penetration -
the act of entering into or through something; "the penetration of upper management by women"