From Halopedia, the Halo wiki
- As overpopulation and political unrest on Earth increase, a number of new political movements are formed across the human colonies within the Sol system. The most noteworthy dissident movements of the period were the Koslovics and the Frieden.
- The Jovian Moons Campaign begins: Jovian Frieden secessionist attacks on United Nations colonial advisers on the moon Io lead to three months of fighting between the United Nations military and Frieden forces. Though this is not the first armed conflict in the Sol System, it is easily one of the bloodiest, and is generally considered to be the spark of increased friction and militarization that followed. The conflict escalates tensions, as Earth's national governments, many of which sponsored colonies within the Sol system, begin fighting proxy wars off-planet. As these continue, tensions on Earth mount, leading to a number of armed conflicts on Earth itself.
- Xbox.com/Halo - Timeline