The Thousand Day War took place between 2086 and 2088. It began 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. They suffered heavy casualties on the way in.
Having already lost their space fleet and feeling themselves at a major tactical disadvantage, in the early days of the war the Ice Warriors tried to intimidate the humans by destroying Paris with an asteroid, a gambit that misfired badly. (NA: Transit)
The humans only suffered one defeat in battle in the Thousand Day War, in the Viis Clarr/Valles Marineris valley. Supreme Grand Marshall Abrasaaar Urr'n'Jaas 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 to storm 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, most 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. It had the capacity to assess and respond to future Martian aggression; it would remain dormant and forgotten for twenty-five years until mistakenly activated by an unrelated incursion.
A group called the Martian Axis formed after the war. They wanted peaceful co-existence with the Martians, but soon began to incite civil disobedience. (NA: GodEngine)