In Bleach, Ichigo Kurosaki and his Soul Reaper allies faced not one, but two evil armies, both of which aimed to reshape the world in their own image. First, Ichigo took down Captain Sosuke Aizen and his Arrancar army, and then an even older foe returned: the Quincy clan, which organized itself into the Wandenreich in the 1,000 years after its defeat.
For centuries, the Soul Reapers were certain that all the Quincy were gone, but they were severely mistaken. Although the Quincy suffered defeat at the hands of their Soul Reaper rivals long ago, they didn't die out. Instead, the Quincy went into hiding, gathering strength and waiting for their chance to strike back, and Soul Reapers never even saw them coming.
How & Why Yhwach Created the Quincy Wandenreich
1,000 years ago, the Quincy king, Yhwach, formed a large empire on Earth called the Lichtreich, or Empire of Light, but it eventually fell. So, Yhwach and his fellow Quincy retreated to where the Soul Reapers would never think to look: the Seireitei, right there in the Soul Society. Once the Quincy enveloped themselves in the shadows with their spirit energy, they seemingly vanished and the Soul Reapers declared victory. There, in the energy-rich Soul Society, the newly-formed Wandenreich gathered strength over the centuries, waiting for the right time to strike back. But the time would not come soon -- Yhwach needed 999 years to regain his strength, body and spirit, and only when he was back in fighting shape did the Wandenreich finally make its move in Bleach during the Thousand-Year Blood War arc.
The Wandenreich, or "Invisible Empire," appears to be an entirely militaristic place, with no obvious civilian infrastructure or social classes. The overall leader is, of course, King Yhwach himself, with his right-hand man, Jugram Haschwalth, as his advisor. Anytime Yhwach is asleep, Haschwalth serves as Yhwach's substitute, borrowing his The Almighty power to make sure it is always available. Also near the top is the Schutzstaffel, four Quincy who serve as Yhach's personal bodyguards and are among the strongest Quincy of all.
The Wandenreich's rank equivalent to Captain is the Sternritter corps, or "Star knights," and the four Schutzstaffel members double Kas Sternritter. There are 26 of them, including Yhwach himself, and each one has a Schrift, or a letter of the Roman alphabet, that gives them a unique power. Yhwach's power, The Almighty, is the "A" Schrift, and Jugram Haschwalth has "B," for The Balance, and so on, all the way to "Z," The Zombie, the ability that Giselle Gewelle wields. The Sternritter are nearly equal to the Soul Reaper Captains in strength and are certainly more numerous, allowing the Wandenreich to pose a serious threat based on that alone.
The Wandenreich is also home to many Soldat, or soldiers, basic Quincy who follow the orders of the Sternritter in battle. During the initial attack on the Soul Society, for example, Sternritter "N" Robert Accutrone opened a gate to allow entire platoons of Soldat to rush into the Seireitei and wreak havoc. Some Soldat are members of the Jagdarmee, or the Hunting Corps, and are tasked with scouring places like Hueco Mundo to conscript new warriors into the Wandenreich. Sternritter "J" Quilge Opie commands the first Jagdarmee, in particular.
The Locations & Territory Of The Wandenreich
By the time the Soul Reapers became aware of the Wandenreich's existence, the empire already controlled a startling amount of territory in more than one world. The core of this invisible kingdom is a shadowy alternate city superimposed on the Soul Society, including countless stark white buildings and a capital hall, Silbern. Silbern is a large palace where Yhwach and the Sternritter reside, and Quincy can easily travel across Silbern or the city with metal plates called Gates of the Sun. Later on, after Yhwach absorbed the Soul King personally, he formed a new palace to rule the new world that he intended to create, a floating Wahrwelt.
The Quincy wanted even more territory before attacking the Soul Reapers, so they turned their sights on the desert world of Hueco Mundo, the place that King Barragan and Sosuke Aizen had once ruled. The Quincy hate Hollows and are poisoned by their touch, but that didn't stop them from assaulting Hueco Mundo and annexing it to the Wandenreich. The Jagdarmee killed or recruited countless Hollows, and the palace of Las Noches was destroyed. Its ruins were eventually used as a camp at some point by the Jagdarmee.
Once enough Arrancar were conscripted to serve as disposable soldiers, the Wandenreich turned its attention to Soul Society itself and launched its assault after a team of Quincy personally declared war on Captain-General Yamamoto. The Wandenreich was ready to announce its presence, and Soul Society was shaken to its core.