STRATEGY FOR OFFENCE
Unlike Mindoir, the overall objective of the batarians in 2176 was to seize the colony at Elysium permanently and start the war that both sides had been preparing for years. This was a major undertaking in comparison to the raiding operations that had been the mainstay of the conflict until this point. It would require sustained naval operations, in which the Systems Alliance would arguably have an advantage. Supply lines from batarian space would also have to be both secure and well organised, presenting new challenges to a military used to being able to carry all it needed for lightning attacks rather than relying on resupply. Military forces and colonial administration would need to be transplanted onto the planet immediately to press batarian law upon the populace, the manpower for which would be considerable. The batarians alone most likely could not have fulfilled these requirements. They were not alone, however. A coalition of Terminus pirates and mercenary companies stood ready to assist them, under the leadership of Elanos Haliat. It was he who would plan and bring to realisation the attack on Elysium.
Haliat's proposed conditions for a victory were threefold. The first was that the Alliance ground forces would need to be annihilated or captured. He came to the conclusion that human forces would rather fight to the death than surrender, but that civilians and militia would likely not possess the same resolve. Furthermore, he believed that any surrender would only ever be partial, and that a highly organised guerrilla campaign could render the planet useless as either a staging ground or an economic hub. Large numbers of troops would be needed to prevent this outcome, and elite forces would be required to deal with the Alliance garrison.
The second condition was that the Alliance Navy would have to be defeated as soon as they arrived to relieve the planet. Human military doctrine demanded a swift counterattack to reclaim any lost colony, and so the assault force would have to possess significant naval assets to protect the ground troops and supply lines. Elysium was not the only planet in the Vetus System requiring the attention of the assault forces either. Sidon was known to be inhabited, as were a number of asteroid stations and the fuel depots orbiting Joppa. They would need to be bombarded or captured Only the batarians could provide the ships for these purposes, as the pirates' own ships had proven to be less than a match for the Alliance Navy's own vessels in open-ended engagements.
The last condition was that imposing order on the colony would have to be swift and merciless. Unlike most colonies in the Verge, the people of Elysium were not used to being under the constant threat of attack. While this might allow an easier initial conquest, any permanent occupation would face ever increasing resistance. This would be exacerbated by the numerous Alliance arms dumps that undoubtedly existed all over the planet. Elysium was also a popular retirement destination for Alliance veterans. All of this meant that suppressing resistance would be far more difficult than what the batarians had experience of before, as even if the Alliance forces were defeated, the civilians themselves would have both the means and the capability to fight on their own. Avoiding a lengthy assymetric conflict by breaking the populace's will to fight would be an absolute necessity.
With these requirements in mind, Haliat laid out his plan to the Arch-Hegemon about two weeks after the destruction of the SSV Amaterasu.
It would begin with the joint batarian and pirate fleets entering the Vetus system in full force. Their initial objectives would be the colony's extensive orbital defences and the fuel stations. The latter were particularly important if the system was to be used to resupply batarian strikes into Alliance space after the invasion. Their attention would then be turned towards guarding the mass relays against the Alliance counterattack. FTL comms to the rest of the galaxy were to be cut immediately. For this, the Batarian Hegemony would provide its First and Second Fleets, which contained the most modern ships of all classes. These would be augmented with flotillas from thirteen independent Terminus colonies, six of which answered directly to Haliat. Overall command of these forces was placed in the hands of Dhark Ar'dra, the Arch-Hegemon's cousin and the same man who had commanded the batarian navy at Mindoir with great competence. In addition, thousands of civilian transports were requisitioned for use as troop transports and cargo haulers. It was to be the largest fleet ever assembled by the batarians for a single operation.
The next phase was the invasion of Elysium itself.
The plan reflected turian military thinking far more than batarian strategic ideology. Some of the lessons of Mindoir were applied directly. The elite External Forces and the best Terminus mercenaries were to be deployed first to bracket the Alliance forces inside their bases. These pockets would then be destroyed from orbit with towed asteroids and deorbited space stations as the rest of the troops were disembarked. This was insisted upon by General Gadnalak, pointing out his failure to break the Alliance strongholds on Mindoir. Haliat was happy to agree to the terms. He understood that any human forces that survived would cause continuing problems, and every hour that passed without their destruction would give hope to the populace for their rescue. The terrain of Elysium was also alpine, very disadvantageous for any assault against the mountain fortresses that the Alliance had built. Cutting the human soldiers off from their civilians was the objective.
In line with turian doctrine, the cities were to be pacified by force. The population was to be given a stark choice, surrender or die. Those that chose surrender were to be moved to safe zones on the outskirts, to remove them from the battlefield and begin the process of enslavement. Those that refused to be moved to a safe zone were to be killed. Batarian regulars were to go street-to-street, door-to-door to accomplish this task. Given the large population of Elysium as well as the inevitable presence of militia and police forces, millions of troops would be needed. Losses were expected to be minimal in this part of the operation. Even with the use of far less competent troops, the sheer numbers deployed were expected to be able to overwhelm any defence the citizens themselves could mount. This part of Haliat's strategy also reflected the demographic nature of Elysium. There were many non-humans on the colony, and he was counting on their lack of will to fight the humans' battle to encourage surrender.
With the system secure, hopefully including its supply and logistics infrastructure intact, the front role would return to the batarian navy. Haliat viewed an Alliance counterattack as a certainty, an accurate reading of the human attitude to aggression if ever there was one. With Elysium in his hands, he expected that he could ambush any force that the Alliance could bring to bear quickly and that he could cut their supply lines using his massive flotillas of pirate vessels. He calculated that the Alliance fleets would not gather fast enough to overwhelm his own before the general conflict started, leaving him in control of the system and in an excellent position to continue offensive actions through the rest of the Verge.
Arch-Hegemon Ar'dra was very pleased with the plan once its final form had been presented to him, and congratulated his turian ally on the grandiose nature of the operation. He considered it entirely worthy of being entered into the immortal annals of history. As it turned out, this was indeed the case, but not for the reasons either Ar'dra or Haliat thought.
STRATEGY FOR DEFENCE
Alliance military strategy underwent a transformation with the arrival of a new government. The 2173 White Paper on Defence and Colonial Affairs outlined a radical departure from the defensive and diplomatic thinking of the past decade and a half. The lessons of Mindoir had been hard militarily as well as politically. Defence spending in proportion to current holdings was abandoned as a concept. Expansion had outstripped the ability of the Alliance to defend its territory for a decade by that point. This was seen as tolerable previously by many in the Alliance, whom believed that the Citadel Council would intervene in any major conflict to protect its own economic interests. This notion was completely obliterated by Mindoir and the First Verge War. Not only did the Council not aid the Alliance in its time of need, but they forced humanity to sign an unacceptable treaty with the batarians, a treaty that was promptly broken.
Before 2173, the Alliance maintained a minimum deterrence strategy and a no-first-strike policy, whereby it would build and maintain both conventional forces and WMDs in numbers just sufficient enough to put off potential aggressors. Under Taro, this was scrapped as a complete failure, as the strength of the Alliance had spectacularly failed to deter the batarians. The policy was replaced by "massive retaliation". Humanity committed to respond to any open aggression with an overwhelming, disproportionate response. As such, both conventional forces and WMD programmes were expanded. Humanity's military capability was to be brought up to a standard capable of effectively deterring any potential foe, including the Citadel species. The consequences of this change would reach far beyond the conflict with the batarians, and arguably was a key factor in the survival of the entire galaxy during the course of the Reaper War. However, at the time, the decision was extremely controversial and threatened to derail human relations with the Citadel.
Elysium was not immune from these trends, and from 2173 onwards, the so-called Jewel of the Skyllian Verge prepared its defences in depth with generous funding from the Alliance Parliament. They included deep-space stations, asteroid bases, reinforced mountain complexes, and advanced ground-to-space defences. Many of these preparations were conducted under the guise of civilian projects, concealing them from the greater galaxy's eyes. This detail was a necessity, as a quarter of Elysium's population was non-human.
In addition to the change in military doctrine and the increase in defence spending, Consul Taro greatly expanded the scope and resources of the Alliance intelligence services. The Army and Navy intelligence services were merged into the Defence Intelligence Directorate, or DID, and set to work against the batarians and their pirate allies. Particular attention was given to recruiting dissident batarians in exile from Hegemony space, as well as infiltration of the criminal underworld of the Terminus Systems. Signals intelligence was also made a priority, and by 2175, the DID had extensive networks of both agents and listening posts. These would pay handsome dividends.
Elanos Haliat's plan of attack was leaked to the Alliance almost as soon as it had been finalised. At first, the DID believed their agents had been compromised. The scale of the proposed attack amounted to the first blow of total war, a conflict that the Hegemony could not possibly win. However, when message interceptions and reports of troop movements came in, the reality of the situation could no longer be ignored. The news was reported directly to the Consuls to avoid notifying the batarians that their plan had been discovered. We are told that the leaders of humanity received the news with calm resolve. The war that Taro had been waiting for was about to arrive.
Alliance High Command put forth a plan for a pre-emptive strike on the batarian staging areas, with the Navy entering the systems in question from multiple relays and then going on the attack. Consul Taro strongly opposed the idea. She believed the batarians would simply retreat through the relays to their more heavily defended core regions, and the war would devolve into one of attrition. Furthermore, it would fail to inflict the sorts of losses that would scare off the Citadel from intervening. Nothing short of a comprehensive defeat of all forces committed to the attack would accomplish Taro's political and military goals. If she was going to establish humanity's place at the top table of galactic politics, not to mention win the approaching 2177 general election, she would need just that.
The Consul ordered that a new plan be drawn up to trap the batarian and pirate forces. The operation that Alliance High Command came up with was perhaps even more ambitious than the one the batarians planned to put in motion.
Firstly, the batarians would be encouraged to believe their plan was going almost perfectly. The combined Terminus-Hegemony fleet would be allowed to enter the Vetus System entirely unopposed in space. To prevent their use by the enemy, the fuel depots orbiting Joppa would be sabotaged along with those in neighbouring star systems. Furthermore, the full measure of enemy ground forces were to be allowed to land on Elysium itself. In effect, the plan called for giving the batarians the illusion that they were pulling off a spectacular coup, while positioning as many of their available forces as possible right into the jaws of a huge strategic ambush. The plan would rely on the defenders of Elysium holding out long enough for the Alliance to spring the trap, but there was high confidence that the batarians would land as many troops as quickly as they could. It was calculated that the defences would only need to hold out for twenty four hours before reinforcements could arrive. To assure that they would hold, a front line Alliance Army task force would be sent to defend the planet, disguised as a regular transfer in the garrison rotation.
Once the batarians were committed, the counterattack would begin. Four Alliance fleets, fully half the available naval power of humanity, would be committed to the campaign. Three of these would attack directly from Alliance space, using relays that the batarians would be sure to guard. The fourth would skirt around the Verge through salarian-held space, and then break into the batarian rear via their own supply lines. The enemy fleets would be trapped in the Petra Nebula, and attacked continuously until they were destroyed. In addition to this, a single legion of the Alliance Army would be dropped by assault titan onto Elysium, which would then go on the offensive against all batarian and mercenary forces. Once the assault had been utterly crushed, the Alliance would begin offensive operations against the unprotected staging areas and would seize them as forward operating bases.