From Halopedia, the Halo wiki
Delambre is an impact crater on Luna.
Battle of Delambre
The Delambre crater was the site of a brief armed conflict between two factions of the Frieden movement; the conservative Friedenists, and the reformist Neo-Friedenists. As the UNSC prepared to occupy the crater, the Neo-Friedenists took advantage of this opportunity and began furthering their own ideals (which included negotiating a peace treaty with the UNSC), and turned against their more hardline namesakes.
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