From Halopedia, the Halo wiki
Mamore was heavily involved in the Insurrection and rebel violence against both military and civilian targets was frequent. In 2511, a terrorist bomber from the Freedom and Liberation Party detonated a commercial nuclear explosive in the Haven arcology, killing 2 million people and injuring 8.3 million others. This attack prompted the UNSC to increase its military presence on the colony. Chyler Silva's parents, both of whom were UNSC military, were part of this response and her family moved to Mamore as a result. Both of her parents were eventually killed in action against rebels.
At some point prior to 2526, lieutenant commander Hector Nyeto read a number of ONI reports that discussed the SPARTAN-IIs effectiveness against the local rebel leadership on Mamore and Jericho VII.
SPARTAN-B312 participated in a counter-insurgency operation on Mamore on May 10, 2552. During the operation, the SPARTAN's talents as a Sabre pilot were exhibited. This won Colonel Urban Holland's approval and led to the SPARTAN's assignment to Noble Team.
Private Dorking was from Mamore and Rani Sobeck threatened to send him back during the raid on Chawla Base. Sobeck also mentioned the Kelorists, who are all from Mamore. The group has unique tattoo, a cross in a circle, that they use as a symbol of their association as a Kelorist.
The colony is likely named after the Mamoré River, a river which constitutes part of the border between Brazil and Bolivia. This is also suggested by Mamore having a province named Mato Grosso, which shares a name with a Brazilian state.
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