From Halopedia, the Halo wiki
Asmara was a human colony in an unspecified system. Sometime relatively early in the Human-Covenant War a battle took place on Asmara, which involved Gage Yevgenny's team of Orbital Drop Shock Troopers. One ODST to die in the battle was Mason, after a Sangheili speared him along with ten other ODSTs with an Energy Sword before Gage got off a near point-blank shot with a missile launcher.
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