The Imperial Banner

Even in modern politics, a political atmosphere cannot be stable with only a single dominant super-power.
The Republic stood for millennia as a federated galactic superpower, growing complacent with the relative stability of its golden age. However, peace and tranquility equates to some as boredom.
They start looking for flaws the masses do not notice or do not care to notice. One man, an advocate of a strong central government based on a wide meritocracy, Piotr Smertiev, was one of those bored people. When some continued quiet discontent or open acts of terror or protesting, Smertiev applied a proposal to the Republic government.

The Republic had at times created Political Experiment Zones to test certain forms of government. Some worked, some didn't. Lessons learned were usually grafted into the Republic workings and furthered political theoretic studies. Smertiev's proposal outlined a form of government, where the central power served as a monolithic pillar for the state, where individual political and social merit would be weighed in selecting officials and rulers. His proposal was taken into consideration, and passed. The seeds were sown for the Empire.

The Empire started off with a few dozen systems, where each system was controlled by a centrally appointed governor, and at the center there was the Party machinery.
The experiment zone was ruled by a single political faction know only as the Party, which could be classified a statist meritocracy. Before the Empire broke off, clear rules were followed in the order of succession for the different offices and positions, even that of the supreme ruler.
The Emperor, as the position became known later, was not an inherited title, but a semi-voted one, attained through painstaking machinations of public opinion and politics and the working of the meritocratic system. Only the previous emperor can nominate the next emperor and s/he had to be approved by the emperor's council.
After the Party had consolidated its power over the governed worlds, and established their mandated internal security and defense force, the political experiment zone declared its unilateral independence from the Republic as The One Humankind Empire, along with some bordering constituent states and colonies who shared in their ideals. After this the rivalry between the two has lasted for eons. One calling the other the Evil Empire, the other being the Corrupt Lapdogs (the imperial lingua franca, Sprâk, has a pun based on the sound of their word for "parliament"). These two polar opposites have gone to war several times, always keeping a tense cold war in between.

After breaking off from the Republic, the Party became so intertwined with the workings of the Empire, that it is simply known as the system.
The empire is the party in its entirety.
As the Humankind Empire is an empire, many of the appointed officials, rulers and governors took up noble or royal titles, using their positions to make their offices practically hereditary. The system of meritocracy allows the sons and daughters of officials to have as much consideration for offices as other highly educated candidates, if not more so due to their wealth and chances to attend the most prestigious institutions with little effort.
Each office is assigned by the one higher to it: The emperor appoints the ruling council of 12 oversector governors (the kings), who in turn approve the next emperor; the "kings" appoint sector governors (the grand dukes); the "grand dukes" appoint system governors (the dukes); the "dukes" appoint planetary governors (the counts); the "counts" appoint continental chiefs (the viscounts); the "viscounts" appoint regional chiefs (the barons); the "barons" appoint city chiefs (the baronets); the "baronets" appoint lower party officials (the gentlemen).
Each office is responsible for the collection of taxes in their area as well as keeping order in their respective fiefs. Each office is a vassal to the higher one, so the higher office has control but no direct rule over a fief.
For example a duke can hold a territory of his own, but the rest of his area of responsibility is dealt out to those he has appointed as counts that serve as his vassals. These vassals have vassals of their own, and they are loyal to their own liege after the emperor.
Thus a duke holds less power over a baron than does that baron's count.
Each step can dole out smaller fiefs and these fiefs determine the rank of an official. A grand duke has dukes under him, but he can also appoint a baron to any of his own holdings if he so wishes.
Upward mobility is immensely limited, thought it can happen. A commoner can get the attention of his baronet and be inducted into the party. Given enough time and merit (usually through machinations of the noble game, military prowess or controlling the masses) an official can rise to nobility. Even to the position of a king if they live long enough. It has been estimated it would take four generations for a common-born family to rise close to the Imperial Throne, and even that is generous.

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The Eagle is an amalgamation of the symbols of two evil (in my opinion, at least) states: 3rd Reich and Russia. The basic design of the eagle is the same as the nazi eagle, just with two heads (this symbolizes the belief of the Party: "the state is the people, the people are the state." Individuals are expendable).
The banner represents another belief of the Party: the Lone Earth amidst the darkness of space, ruled and guided by the Party to dominance. The Party is a populist, human-supremacist, dictatorial, feudalistic meritocracy.