Côte d'Azur
From Halopedia, the Halo wiki
Côte d'Azur was the main population center of Sigma Octanus IV, a UNSC colony world in FLEETCOM Sector Three.
In the year 2552, the Covenant launched a small attack against the Sigma Octanus system in hopes to retrieve a Forerunner artifact that was on display in a museum on Sigma Octanus IV's surface. During the invasion, Côte d'Azur was destroyed when Spartan-117 detonated a HAVOK Nuclear Warhead underneath the city streets in order to prevent the Covenant from finding anything else of value. The planet, however, still remains under Human control.