The Unification War is a war that takes place before the events of Cyberpunk 2077.
History
The Unification War was a war between the New United States and several secessionist states. The war caused Night City to secede from the Free State of Northern California and became an independent city-state. The megacorp, Arasaka, returned to Night City and put it firmly under their control by weakening the megacorps within the city.