The first planet to be colonized, Mars early became the second most populous planet after Earth.  Mars was one of the founding members of the Planetary League.

The Mariner Valley Incident in GSC 16 was a huge landslide that killed many colonists, and an important early event in the history of the Tardigrades. 

One hundred years after the Mariner Valley Incident, a large, bronze sculpture, called "The Bell of Remembrance" was placed at the site.

Mars was the birthplace of Amadeus Krieg.

History

GSC 58, The Cydonia Incident: A group of Markovian researchers was caught performing unethical experiments, turning public opinion against the Markovians.

During the Great Reckoning, Mars was conquered by the Holy Empire of Man.

During the War of Galactic Unification, Mars joined the Galactic Republic.