The Battle of Delambre was a presumably small-scale conflict that plummeted the Frieden fascist movement into a civil war between the conservative faction of the organization and the reformist Neo-Friedenists.
At the conclusion of the Rainforest Wars, certain dissenting groups arose within the Frieden movement that promoted reformist ideals. The Neo-Friedenists was formed in 2162, challenging their original founders and expressing their wish to negotiate a peace treaty with the UNSC and end the Interplanetary War.
As UNSC forces approached the Delambre crater, the Neo-Friedenists took up arms against the conservative side of the Frieden movement. It is presumed that the Neo-Freidenists won the brief engagement, as they later attempted to discuss a peace treaty with the UNSC.