The war initially started out as a mere conflict between the Earth-led colonial government of Mars and group of militarist radicals (the SDF) but eventually escalated into a full-scale war and spilled over, spreading out into the rest of the Solar System. This war took place 30 years prior to the events of Call of Duty: Infinite Warfareand is named as such due to the SDF's secession from the nations of Earth that became the UNSA. The Secession Wars was a conflict between the nations of Earth that became the United Nations Space Alliance and the Settlement Defense Front. Strength Earth Forces that became the UNSA Solar Associated Treaty Organization Combatants The nations of Earth that became the United Nations Space Alliance