From the desk of the Commander:
Since it appears this information will be relevant once again, I have had the Keigun compile a summary of the events surrounding the SQN invasion and the Battle of Hueco Mundo for those who were not among us during the Age of Turmoil.
Sine Qua Non Edit
The Sine Qua Non, or SQN are at their very simplest, a collection of rogues who have banded together to form a quasi-military force. They share no common background or motivation other than a commitment to overthrow the king and his protectors, the Gotei 13.
Earliest intelligence reports point to the few years following the First Siege of Seireitei to be when the SQN truly began as an armed body. There have always been anti-Seireitei militants, but the fact that the Gotei hid behind the Seireitei walls to stave off the attacking hollows, leaving the outer districts to their own devices was the issue that truly galvanized the scattered anti-royal pockets and united them under a single banner.
Their command structure is rather chaotic, although during their attack, three lieutenants emerged. One was captured, one escaped and the other was killed. Above the lieutenants are the heads of the movement who, even 500 years later, remain a mystery.
The SQN, being composed of ex-shinigami, mercenaries, greedy street thugs, religious fanatics and fugitives should have fallen apart when fighting against a professional army like the Gotei 13, but they are strangely well trained and equipped, suggesting that their overlords are in possession of vast financial and commercial resources. We currently suspect [CLASSIFIED: C46] of funding the operation.
SQN typically wear white hooded robes to protect their identities, although some prefer to wear a tighter fitting uniform and a mask. Many claim their white attire is to help distinguish themselves from the â€œcorruptionâ€ of the Gotei 13.
Petycon approached the SQN after the First Siege of Seireitei with the offer to lend the support of his Espada to the movement if they would commit to an attack on the Gotei. The SQN, eager to capture Masaru and secure the Ou Ken for their purposes of 'true democracy' agreed to the plan readily, and so the Second Siege of Seireitei began.
Predictably, Petycon ordered his Espada to retreat from the battle early, and left the SQN to their own devices; his intentions obviously to wear the Gotei 13 down for his next strike rather than to aid the SQN in any concrete way. With the Espada gone, the Captains were free to target the command structure of the SQN and the tide turned. A great deal of the rogues were captured or killed, and the SQN was forced to retreat.
While their presence remains a threat, the SQN feed off of discontent among the common people, and with the 500 years of relative tranquility, the sentiment that fueled the rogues has died down considerably.
The attack troubled Masaru greatly and some theorize that having to fight fellow citizens of Soul Society was what precipitated his decision to push for a strike directly into Hueco Mundo.
The Battle of Hueco Mundo Edit
War-weary from the previous two attacks, the Central 46 first laughed off Masaru's request to rally the forces of the Gotei 13 and attack Petycon directly at his fortress of Los Noches. A few decades later, the Central 46 finally relented, hoping that a war abroad might distract the people from the problems brewing domestically.
"Masaru's folly" as the plan was called in the day surprised shinigami and hollow alike, as the forces of Hueco Mundo were ill-prepared for an attack so soon after two consecutive and damaging battles in Seireitei itself. Against all odds, the Gotei 13 routed the Hollow army and surrounded Los Noches before Petycon could enact an effective defense.
Los Noches itself proved to be impregnable as long as the Espada were manning it, and rather than go through a protracted siege, Masaru led his legendary captains to storm the fortress and fight the Espada personally. The move was both his greatest success and his greatest failure.
Petycon, Espada Numero Uno, and his top six generals fell to the blades of the Captains. But they did not fall alone. Of the Captains who entered, only Yukiko Murray and Seisatsu Kuragari left the ruins of Los Noches alive. Murray died of her wounds shortly thereafter. The three weakest Espada fled to the edges of Hueco Mundo, where they remain, presumably.
The Vice-Captains took up the mantles of their predecessors save for Arihito, Vice-Captain of the 1st, whose worthiness to become the new Commander was the issue that sparked the Mask War.
While the Gotei was eventually able to recover from its losses, Hueco Mundo was not. The ability to create Arrancar from Menos was a technique known only to Petycon and it died with him.