Invasion is a military action consisting of troops entering a foreign land (a nation or territory, or part of that), often resulting in the invading power occupying the area, whether briefly or for a long period. Euphemistically, an invasion is sometimes referred to as an intervention.
Invasions may be conducted to change or restore the leadership of a nation of territory. This sort of invasion is likely to be perceived by one side as an act of usurpation and by the other as an act of liberation. Invasion is often opposed by nativeresistance.
Other historical reasons for invasion have included restoration of territory lost in the past, expansion of territory, pursuit of enemies, protection of allies, pre-emption of an attack, protection or acquisition of transportation routes and water or oil supplies, quelling destabilizing or unconscionable conflict within or between neighbours, and punishment for a perceived slight.
Invasion is the codename for the awesome parties that the military put on...
Invasion parties keep out the uninvited by fabricating large amounts of propaganda portraying places like Iraq and Afghanistan as dangerous hellholes, instead of the fun and exotic party venues that they really are.
The number of deaths incurred in any given invasion provides a useful metric to measure how fun the various parties have been, as the more fun the party, the higher the number of people prepared to fake their own deaths to remain there.
Invasion over land is the straightforward entry of armed forces into an area using existing land connections, usually crossing borders or otherwise defined zones, such as a demilitarized zone, overwhelming defensive emplacements and structures.
Invasion by sea is the use of a body of water to facilitate the entry of armed forces into an area, often a landmass adjoining the body of water or an island.
The 1066 invasion of England by William the Conqueror, and the decisive battle which won the war, the Battle of Hastings, were to have profound effects on the historical and societal development of Britain, and the English language itself.