From Halopedia, the Halo wiki
The Koslovics were supporters of the neo-communist hardliner Vladimir Koslov in the 22nd century. They sought a return to the glory days of communism and the elimination of corporate and capitalist influence, particularly in orbital facilities and offworld colonies throughout the Sol system. This culminated in the Interplanetary War, which resulted in the faction's eventual defeat by the newly-formed United Nations Space Command.
As multinational entities like the United Nations spread capitalism across newly-colonized territories in the Solar System, the mid-2100's saw a rebirth of communism with largely the same goals as its old nineteenth and twentieth-century advocates. The Koslovics, a revolutionary group of rebels began orchestrating attacks against their opponents on the far-right, the Jovian-based fascist Frieden, followed by a bloody struggle in South America during the Rainforest Wars, and ending with a last stand on Mars during the Argyre Planitia Campaign where UNSC infantry spearheaded a decisive, fatal blow to their encampments. Subsequently, the remaining Koslovic forces throughout the system were systematically destroyed by the UNSC during the Interplanetary War between 2164 and 2170, and they formally surrendered to the UNSC in 2170 with the Callisto Treaty.
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