Battle of Thessia

The Battle of Thessia was one of the largest, and for the Citadel Alliance most devastating, battles in the High Galactic War. With a massive invasion by Grand Pact forces hoping to break the Citadel Alliance military center, the defending fleets were either destroyed, or forced to retreat. Ground forces consisting primarily of krogan and turians, with geth support later on, landed, and took the Thessia center of government. Remaining Citadel forces retreated to Sur'Kesh.

Prelude
Thessia was the center of the Citadel Alliance's military (prior to the beginning of the war an agreement was made to not involve the Citadel itself), and was the de-facto capital of the alliance. Many individuals, primarily krogan warlords, advocated an all out invasion of Thessia, to crush the Citadel military, and put them back on the defensive, where the Pact had the advantage. Turian military leaders also advocated an invasion. While Emperor Wrex and Primarch Vakarian were both opposed to an invasion, outside pressure forced their hand. Preperations began to launch an invasion of Thessia, and if necessary, occupy it.

Thessia itself was well defended, with the forces being lead by Catanya Betora, the Commander in Chief of the asari forces, and the Supreme Commander of the Citadel Forces. Dreth, the Grand General of the Vorcha was also present. Initially General Sirton Marn was present, but he was called to a different front, and General Mriz Teris was given command of the salarian forces.

First Stage
A vorcha contigent had been stationed near the Thessia mass relay, as a first line of defense. Not anticipating this, when the first wave of the attack fleet arrived, they were caught off guard, and were dealt significant lossess, but as the remainder of the fleet arrived, the vorcha were defeated. Though the bulk of the fleet was intact, the formation was shaken, weakening it slightly.

Second Stage
The vorcha defense fleet, before being destroyed, managed to inform the primary fleet at Thessia about the arrival of the Pact forces. The entire fleet was mobilized, and the two forces crashed into each other. Initially, the battle seemed to be in the Citadel's favor, as it had a slight advantage in numbers, but as the battle progressed, the surperior forces of the turian and the krogan broke the Citadel's formation. With the formation broken, quarian and human transports were given an opening.

Third Stage
After the landing process had been completed, General Asenos (who had been appointed commander of hte invasion fleet) gave the quarian commander, Admiral Gel'Merren, the okay to deploy the geth ships that were stationed outside the system. Geth ships rocketed into battle, catching the Citadel fleet offguard.

Admiral Betora flagship, the Rising Star, was destroyed, and while she surivived, there was no way to contact her. With no clear successor, this sowed futher chaos amongst the fleet. This allowed krogan and turian battleships to further pick off the opposing ships. The battle began to swing more into the favor of the pact, and it opened further openings for geth drop ships, which was one of the initial plans.

Landing
The drop force consisted primarily of turians, krogan, and humans, while quarian ships defended the transports. The landing intially had mixed results, with most asari anti-aircraft cannons still fully functional. However, more than half of the dropships managed to successfully land on the planet's surface.

Advancement
The landing force met heavy resistance from asari forces, as well as vorcha who had been allowed emergency presence on the planet, and advancement was fairly slow. However, they made decent progress towards their primary goal: the anti-aircraft guns. The strategy was to take out the guns so that geth forces could be dropped behind enemy lines, and beat them into submission.

With turian and krogan coverfire, a human division managed to sneak behind enemy lines, and destroyed two of the four targeted towers. The team assigned to the third tower was discovered and killed, while the fourth tower's explosives malfunctioned. Though this did not give the opening that had initially been hoped, it allowed a few drop ships the proper room to manuever.

Geth Drop
A wing of geth ships flew down into Thessia, and dropped multiple geth soldiers into the battlefield, many of them behind enemy lines, catching the asari and vorcha completely offguard. With the geth and humans attacking from the back, and the turians and krogan attacking from the front, defeat was inevitable.

The defending formation was completely shattered, and they surrendered soon after. With nothing opposing them, the remaining anti-aircraft guns were neutralized. With the skies clear, the remaining drop ships landed with relative ease, and advanced further.

Surrender
Word soon reached the fleet that Thessia was falling, and all the forces agreed, despite heavy asari protest, that they could not win. The fleet then retreated into salarian territory, where they regrouped at Sur'Kesh.

The asari Grand Secretary managed to evacutate the planet, and while this kept the asari center of government operating, Thessia's capital city collapsed. The governor soon surrendered upon hearing that the fleet had left. The remainder of Thessia was subjugated soon after.

Aftermath
The Battle of Thessia, while a Grand Pact victory, was costly. Nearly a third of the fleet was destroyed, and many casualties were accounted on the ground battle. This later brought the issue of the occupation. The only two governments who were willing to occupy the planet, was the Turian Hierarchy, and the Krogan Empire. The turians decided to let the krogan do it, as they had taken slightly fewer casualties.

Thessia became, for all intents and purposes, part of the Krogan Empire. Warlord Lazatag Gras was installed as planetary govenor, and a krogan force was garrisoned on the planet. This defeat had a resounding effect on all asari, as they could never in their wildest dreams imagined that another race, much less the krogan, could successfully conquer their homeworld.

This was a devastating defeat for the Citadel Alliance, who had lost their center of operations. It was reestablished on Sur'Kesh, and the remaining fleet managed to reorganize itself. Admiral Betora, who had been rescued prior to the retreat, was stripped of her position as supreme commander, and General Marn was installed as the commander.