Long thought to have intellects marginally above those of wild animals, Martians were gigantic lumbering brutes. In its efforts to colonize Mars, humanity encroached on the Martian habitat. At first, they were viewed not unlike bears.
Leave them alone, and most of the time they'll leave you alone.
Something, still the subject of much debate, triggered their rage.
In 2068, more than ten years after the first Mars colony was established, the Martians began an all out assault on the colony. The natives were violent to the point of wanton cruelty. They taunted and tortured the colonists. They attacked with cunning efficiency. It was a massacre.
Stunned by this sudden violence and enraged by the horrors captured on vidcam, Earth struck back. Hard.
For the first time in its history, Earthers attacked beings not indigenous to their home world. And for the first time, Earthers hunted an alien race to extinction.
It would not be the last.
In 2075, the last known Martian was killed. A number of the Martian bodies were rendered into trophies and are on display in several museums. A few even tour on the carnival circuit out amongst the colonies.