By the year 2199, humanity had attempted to terraform only one other planet, Mars. Past settlers on Mars eventually succeeded in altering the planet's atmosphere enough to sustain a liquid water sea filling Amazonis Planitia. These efforts were interrupted in the 2180s by the devastation of the Second Inner Planet War. Sometime after the war, surviving settlers were evacuated to Earth, and terraforming work was abandoned. The Martian sea remained stable for some time afterward ("Messenger of Iscandar", "Farewell to the Solar System").