The Thousand Day War was a war which took place between 2086 and 2088, beginning with an attempted Martian invasion of Earth in the form of a blitzkrieg attempt at areoforming.
The first day of the human counteroffensive saw the United Nations Third Tactical Response Brigade -- comprised mostly of Irish and Ethiopians -- under the command of Brigadier Yembe Lethbridge-Stewart drop onto Olympus Mons, suffering heavy casualties on the way in.
Having already lost their space fleet and feeling themselves at a significant tactical disadvantage in the early days of the war, the Ice Warriors attempted to intimidate the humans by destroying Paris with an asteroid, a gambit that badly misfired (NA: Transit).
The humans only suffered one defeat in battle inthe Thousand Day War in the Viis Clarr/Valles Marineris valley. Supreme Grand Marshall Abrasaar Urr'nJass set a trap which killed fifteen thousand humans and ten thousand Ice Warriors.
By 2088, forty-five thousand humans had died in the war. The war was finally won when Earth troops were transmatted to Mars, storming the Ice Warriors' base of operations. The majority of the ruling council known as the Eight-Point Table were executed. (NA: GodEngine, The Dying Days) Though some military nests remained in suspended animation, the majority of the surviving Ice Warrior population evacuated the planet and resettled on a world that would become known as New Mars. (NA: Legacy, NA: GodEngine, BNA: The Medusa Effect)
After the war
The human victory was so complete that Mars become a colony world. As a precaution against sleeper nests, an intelligent system named JERUSALEM was installed in the Jacksonville infrastructure with the capacity to assess and respond to future Martian aggression; it would remain dormant and forgotten for 25 years until mistakenly activated by an unrelated incursion.
A group named the Martian Axis formed post-war that wanted peaceful co-existence with the Martians, but they soon began inciting civil disobedience. (NA: GodEngine)