YoRHa: Pearl Harbor Descent Record - A NieR:Automata Story 03

The four YoRHa unit survivors of the Pearl Harbor Descent work to carry out their mission to take back the Earth from the machine lifeform invaders alongside members of the Resistance, androids who were sent to Earth 200 years prior. Together, the group breaches the elevator hall on Mount Ka’ala, beneath which lies the enemy server they must destroy. Meanwhile, in the YoRHa base that orbits the Earth known as the Bunker, the severely disadvantaged YoRHa unit’s requests for support are all denied by the Commander and the Council of Humanity. What is the true purpose of the YoRHa mission?