Literal:
* Flood: A sudden and overwhelming surge of water engulfing an area, similar to how an invading force can overwhelm a territory.
* Wildfire: A rapidly spreading fire that consumes everything in its path, like an invasion consuming land and resources.
* Plague: A widespread disease that quickly spreads and infects a population, much like an invading army can infect a nation with its influence.
Figurative:
* Virus: A microscopic organism that takes over a cell and replicates itself, similar to how an invading force can infiltrate and control a society.
* Parasite: An organism that lives off another organism, drawing resources and weakening it, much like an invading force can exploit a nation's resources.
* Weed: A persistent plant that takes over an area, crowding out native species, similar to how an invasion can displace existing structures and cultures.
Social/Political:
* Takeover: A hostile acquisition of control over a company or organization, mirroring the forceful seizure of power in an invasion.
* Revolution: A sudden and radical change in a society's political or social system, comparable to the overthrow of existing order during an invasion.
* Immigration: A large influx of people into a new country, potentially causing social and economic changes, like an invasion can disrupt the status quo.
The best analogy for you will depend on the specific context and the nuances you want to emphasize.