Defense of Mars

In late 2552 during the Human-Covenant War, the UNSC defended Mars from attack by Covenant forces.

Argyre Planitia
On October 13, 2552, gravitic and radiation anomalies were detected near Argyre Planitia. A team was sent to the site and a cloaked sensor platform of unknown origin was discovered, triggering WIDEAWAKE. Fleet Admiral Joseph Harper issued a stand-down order after discussing with Admiral Margaret Parangosky.

Battle
Due to extensive infrastructure, Mars was a major target when the Prophet of Truth fleet arrived in the system. as they headed toward Earth. This resulted in several key battles on the planet.

Mare Erthraeum
UNSC Army forces led by Colonel James Ackerson fought the Covenant on Mare Erythraeum on the surface of Mars. It occurred simultaneously with the Covenant's prolonged invasion of Earth and resulted in a Covenant victory. After the UNSC's eventual defeat on Mars, the Covenant began to concentrate more of their forces on Earth, although Ackerson's work in this battle helped buy UNSC ground forces on Earth precious time. During or after the engagement, Colonel Ackerson was taken prisoner and taken aboard the Triumphant Declaration.

Aftermath
Although the Martian defense forces were eventually crushed, they are credited for delaying Covenant forces from pressing their siege on Earth.

Mars and Luna were hit particularly hard although both fared better than Earth.

List of appearances

 * Halo: Uprising
 * Halo: New Blood
 * Halo 5: Guardians
 * Limited Edition dossiers
 * Halo: Divine Wind