- "We fought back. We'd known war. But not like this. White Martians had been toiling underground, building weapons of death. Fire traps. Their technology overwhelmed us. There was no honor in how they fought."
- —J'onn J'onzz[src]
The Martian Civil War, also known as the Green Martian Genocide and the Martian Holocaust, was a conflict between White & Green Martians that ended with the presumed extinction of all Green Martians, aside from M'yrnn, Malefic and J'onn J'onzz. The genocide was perpetrated by the White Martians another races of Martians that lived beneath the surface of Mars. The genocide brought about the end of the Green Martian civilization and secured White Martian dominance over the planet.
For a long time Mars had been at peace and the two martian races had been separated with the Greens living on the surface and the Whites living underground. For some unknown reasons the White Martians emerged onto the surface of the planet and directly sought to end the Greens with some fanatic conviction. The Greens tried to fight back but the Whites overwhelmed their defenses and destroyed any opposition to them.
The emergence of the Whites brought them into direct conflict with the Greens. Malefic J'onzz betrayed the Green Martians during the war and helped the White Martians kill his own kind. For that, the council sent him into the Phantom Zone and wiped any memory of him from the collective consciousness. Later, the Whites ruthlessly subjugated the Greens and killed many outright including woman and children. The men were forced into labor to work for the Whites until their death. The killings was systematic and without mercy as the White Martians sought to bring an end to Green Martian race.
- The holocaust is similar to the Holocaust of the Jews during World War II.