Battle of Mesra

The Battle of Mesra was a battle fought on the human colony world of Mesra between the forces of the United Nations Space Command and their allies, against the Covenant.

Background
In 2525, the Covenant declared war on humanity, beginning the Massacre of the Outer Colonies. The initial Covenant invasions saw the majority of human worlds they encountered such as Harvest, Etalan, Biko and Redstow VI - among others - subject to intense orbital plasma bombardment - a process known as glassing.

The planet Mesra was an Outer Colony, notable for rich deposits of xenotime - a compound that yields ytterbium and erbium - lanthanides critical to the manufacture of fusion reactors and lasers - among other other lanthanide ores. As such, the planet was targeted by the Covenant and spared the orbital bombardment usually given to human colony worlds, instead deploying invasion forces onto the surface with the presumed intent of capturing these strategic resources and mining infrastructure intact.

Early resistance
The Covenant resistance to simply glassing the planet led to the intelligence analysts of Battle Group X-Ray to conclude that the Covenant goal was to capture Mesra's mining infrastructure, leading to a large deployment of Marines onto the planet in an asset denial operation. Consisting of the 24th Marine Engineering Brigade, the goal of the UNSC operations on the planet were to destroy not only the mining operations themselves, but use enough nuclear weapons as to make the ore deposits themselves utterly useless. In addition, the planet's native Miltia of Mesra was called upon by Admiral Preston Cole to forgo evacuation to assist the UNSC defensive force; an oath the militia took seriously.

Over the ensuing eight days, the UNSC, Militia and Covenant fought a gruelling conflict with the Militia proving their determination; sacrificing numerous brigades wholesale to prevent the invaders capturing a single mine. By June 5, 2526, the Militia's forces had been depleted to just one battalion - the Fifth Ghost Battalion - and were low on food, medicine and ammunition; having marched for thirty hours non-stop themselves having come out of two days of battle. By the eighth day of fighting, the humans had managed to successfully repel the Covenant long enough that only one xenotime mine remained.

UNSC backup
With the Militia forces nearly depleted and the Marines on the verge of being overrun, SPARTAN-II Blue Team was deployed onto the planet to assist in completing the UNSC objective, along the way destroying at least one hundred Wraith tanks. On June 5, Blue Team were involved in an engagement at Bogadlan Plain and by June 6, the invasion had pressed the defending forces into Samalat Gorge in the Karpos Mountain Range; a deep canyon coated in thick jungle. The terrain was almost impassible except for some lone mountain roads and the Nasim Bridge. Thanks to Covenant air superiority, air support was unavailable and thanks to the deployment of combat bridging vehicles (CBVs), destroying the bridge would do little to impede encroaching Covenant armoured columns. The Covenant armoured column was primarily comprised of around fifty Wraith artillery tanks, easily capable of arcing their fire over the canyon to hit the defensive force.

To defend, the Militia and Blue Team planted a large minefield (with Lotus anti-tank mines supplied by the Marines) on the side mountain pass on the Covenant side of the gorge consisting of four individual minefields placed between two and five kilometres away from the bridge; to encourage the Covenant vehicles to travel closer to the cliff edge and maybe even fall off. In a more even match-up the Militia would have chosen to hit the Covenant lines well before they got to the Nasim Bridge, though the previous week of fighting had left the forces so depleted such a strategy was infeasible. The last kilometre of land before the bridge was even more heavily mined with additional explosives along the gorge; if the CBVs stopped to deploy their hard light bridges, the explosives would detonate and destroy the Covenant's only way across the gorge. The mines served to slow the enemy advance, with the intent of exposing the vehicles to fire from the defending side of the valley for as long as possible. An additional twelve anti-air missile batteries placed along the mountains served to deter any Covenant air attack. If all went right, the Covenant armour would be prevented from crossing the valley, leaving only infantry forces for the Marines to defend against.

Instead, John-117 proposed an alteration to this plan; if the Spartans could destroy the CBVs, the bridge could be detonated as the Wraiths crossed - leaving the Covenant forces stranded on the other side of the valley and leaving the only available option to be dropship deployment. However, this would deprive the Mesrani forces of their opportunity to enact vengeance on the aliens; leading to a compromise. Blue Team would use their gauss cannons to fire upon the CBVs, while the Mesranis destroyed the bridge before any Covenant forces reached it. The Militia troops would stay on the Covenant-held side of the gorge, raining rocket launcher fire down on the Covenant troops from above, keeping the enemy pinned in the gauntlet. The Spartans considered the plan wasteful of good soldiers, but the Mesrani forces were insistent on killing the enemy.

Covenant engagement
As the Covenant forces approached, the Fifth Battalion's electronic warfare squad began sending out one hundred-thousand decoy transmissions per second as to keep the transmissions of the human forces hidden. Blue Team deployed into the brush with their massive gauss guns, ready to begin sniping at the CBVs as they entered range. The vehicles entered range and the Spartans fired, taking out one bridging vehicle almost immediately. The Wraiths opened fire on the Spartans' positions, though the Spartans were already moving out of the way. Contrary to the plan however, the Covenant did not continue to advance - instead deploying several combat support vehicles to near the front - deploying swarms of over a thousand Yanme'e to begin attacking the humans from above. Meanwhile, the Wraiths continued their artillery barrage on the jungle, intending to drive the Spartans out and flatten as much cover as possible.

In response, the Mesranis began using their Anaconda surface-to-air missile batteries to fire down at the Covenant - to limited results due to the Anacondas' limited ground targeting capabilities. The barrages were successful in taking out roughly two-hundred Yanme'e and dozens of vehicles. In the confusion of the strike, the Mesrani infantry began to advance on the Covenant formation - being almost entirely eliminated with little effort on the aliens' part. Frederic-104 and Linda-058 were assigned to keep firing at the CBVs to prevent the Wraiths crossing the bridge and attacking the Doukala mine, while John-117 and Kelly-087 began to focus their fire on the attacking Drones.

With the Covenant now in danger of overrunning the defense, the Mesranis began to focus their attention on blowing the bridge up; however, the last soldiers were cut down by the Wraiths as the tanks themselves reached the bridge. The majority of the vehicles did not cross, instead waiting for a beachhead to be secured on the other side. The second CBV was destroyed, and the Covenant did not deploy their third to keep it secure - if the bridge were still available, exposing the CBV to fire was unnecessary. At this time, the interrupted the battle to inform Blue Team that they were being extracted on the orders of Admiral Cole - at the behest of the 24th's Brigadier General Artur Pahlavi. With the team ordered to be ready in fourteen minutes for extraction, the situation for the defense became even more desparate. The Spartans realised they were unable to defeat the inbound armour forces any longer and began to pull back to the 24th's HQ for extraction - all the while pursued by the Covenant.

Aftermath
The Spartans arrived back at the Marine HQ five minutes past their deadline, to the annoyance of the prowler's Captain Amalea Petrov. The prowler was landed in a ravine four kilometres away from the xenotime mine and out of the sight of Covenant ground forces. Due to Blue Team's late arrival, the prowler had missed its window for exfiltration, and now numerous squadrons of strikecraft were searching the sky for the prowler. The 24th Marines began preparing a mass evacuation for twelve minutes later, with the prowler intending to hide its exfiltration alongside the Marines. Without the Night Watch's protection, it was likely that the Marine engineering transports were destroyed. Aboard the Night Watch, the Spartans were briefed on their next operation; a landing on Netherop to capture the wreckage of the downed Covenant frigate Lucky Break.

List of appearances

 * Halo: Oblivion