The Republic of Linked Planets
The Republic has an odd beginning. Originally containing one race, The Zarconians, which are a noble and young but quite advanced race that put valor and honour before survival, the Republic has grown to incorporate 5 races, in a cooperative economic, social, and military government.
The government structure is a public assembly, consisting of a bit more than 5000 members, who bring the people's wishes to the senate, a much smaller group of about 500 members, the number of senators assigned to each race are according to the population of their empire; they, in turn, assemble a bill to bring forward to the Supreme Assembly, the ruling body over the entire republic. The Supreme Assembly consists of 11 members; while originally, only the Zarconians had 3 members, due to public distress the majority number rotates around the races, making sure no race has the upper hand forever.
Originally known as the Interstellar Empire, the Zarconians got to a well-off start due to the fact that their physiology has two characteristics: Armored plating in the form of Chitin, and the ability to regenerate body parts in a matter of a month. This allows for riskier endeavors, in deep space, and exploring unknown planets. Due to this, combined with a sort of scientific renaissance, which gave them the synthetic fuel known as Uiffin (Pronounced whiff-in), allowed the empire to grow quickly.
As the Empire expanded, it became more authoritarian in nature, until the government watched over everything. However, the Zarconians had used a successful variation of a feudal monarchy for hundreds of years, and were used to little freedoms.
In the Zarconian year 142 (They start the calender at the first space flight using Uiffin) a colony ship discovered a solar system containing a planet, the third from the sun, that would be suitable for terraforming. What they discovered next, would shock the entire Empire. They had found a world that was already habitable. Containing an abundance of wildlife and foliage, colonists quickly established a colony on a peninsula, near a body of water.
More settlers quickly came, and soon, the capital city, known as Rem'Nah (Hopes' Fountains), harbored over a million souls. by the year 165, The planet named Res (Hope), after one of the first born on the planet, was one of the largest populated colonies in the empire.
More mysteries were soon to be discovered. Some wandering members of a small village discovered an ancient vehicle. In it, was still functioning cartographical technology, pointing towards... something. Being sensible Zarconians, they headed towards that something, in hopes of finding something of value. What they discovered was more valuable then anyone could possibly imagine.
They found a city. A large one, full of life. That is, mechanized life. Thousands of robots, maintaining the city. The small group had just discovered the first piece of evidence of alien civilizations, dead or alive.
Scientists flocked to the city. It was discovered that networks of travel existed to other cities. Robots maintained every city, keeping them in pristine shape. Knowledge was obtained, powerful knowledge. This civilization had been quite advanced before something had happened to it. Within the cities' halls, papers were found, and translated. The discovery of certain language software, and a working machine able to use this software, allowed scientists to quickly translate the language. What would have taken years, took months.
It was discovered that this alien civilization, calling themselves "Humans" were explorers, warmongers, scientists, and merchants. Considering these were all castes in the Zarconian race, it was quite coincidental. As it turns out, it was just that.
The new technologies discovered were astounding. The humans had invented "jumpdrives" before they had disappeared. These astounding works of engineering allowed starships to fold space, and move through at much quicker speeds then Uiffin would allow. Ideas were discovered, philosophies. These philosophies, however, did not agree with the current government. In fact, they agreed with just the opposite.
Ideas of personal freedom, and a governing body chosen by the people and not by blood, were first mentioned by a species of Humans long, long ago. These people worshipped a number of gods, who were omnipotent, yet also vulnerable in ways. The Zarconians did not agree with that idea, but some did like the idea of the ability to govern themselves. It fit with the way that all Zarconians hold themselves up.
So that certain few began their mission in the year 172. They began showing off these ideas, with values more easily accepted by Zarconian minds. The first known speech happened 3 months after the mission started.
Obviously, however, the current government did not agree with this. And thus, the beginning of the Republic.
The Zarconians who did agree with the idea of the population ruling themselves, which was about three quarters of the Resaan population, overthrew the loyalist government and established themselves as the Republia'Res (Republic of Hope). Using the Humans ancient, and powerful technology, the Republic built up a powerful fleet of ships.
However, the Imperial Navy had had a longer time to build up. The battle above Res included the Imperial 3rd and 5th fleet, against the Republican Defense fleet. It was no contest. Republican ships blew through the wreckage, knowing that they had reached the point of no return.
Each succeeding battle ended in victory for the Republic. Using such advanced technology allowed the Republic to keep it's most powerful ships back, and use the smaller ships to win the fights. At the final battle above Zarcon, in 179, the larger ships were called in. The Zeus battleship and Atlas carrier annihilated most of the Imperial Navy. The Republic, had gained control.
As the Republic expanded, they discovered new alien races. Most notably, the Ranaath, a peaceful race that stood over 12 feet tall, and the Jer, an arachnoid race that were remarkable shipbuilders- and soldiers.
The main problem with the Humans' jumpdrives is that they drained a lot of energy. Republic scientists fixed that problem, by accident. While experimenting with elements from Zarcon and Res, an intern discovered that with a mixture of Chlorine and Ernon gas, creates a highly energetic, yet calm, reaction. Due to advances in synthetics, both of these gases were easily made. It also gave off an interesting bluish-green hue.
Ares Heavy Fire Support Destroyer

The Ares class, aptly named after the Humans' god of war, is heavily armed, but loses speed due to that fact. The original model was used in the Revolution, and was highly effective. Like all Zarconian Ships, the Ares uses a mixture of chlorine and Ernon gas to power it's fusion reactors.
Hermes Flak Gunship

The Hermes is a small gunship that was designed to shoot down fighters and projectiles. It's particle flak cannons swivel with ease, able to shoot down most kinetic objects. It also has weak energy projectors that can shoot down fighters. While the Hermes is fast and maneuverable, it lacks in power.
Atlas Carrier

The Atlas class Carrier carries the strikecraft of the Republic's Navy.
Carrying large squadrons of Selene Heavy Bombers and Apollo SSFs, the Atlas enables fleets to have anti-capital ability without capital ships and space superiority. However, due to the size of strikecraft, the there is not much room for gunners, or guns for that matter.
Selene Heavy Bomber

The Selene is a small craft, designed to be held by the Atlas carrier, and carries two torpedo launchers for anti-capital ship combat. It is not that strong against anything else though.
Apollo Space Superiority Fighter

Also designed to be carried by the Atlas carrier, the Apollo is designed to shoot down any bombers or corvettes. While fast and nimble, the Apollo cannot stand up to larger ships.
Mirus Experimental Stealth Corvette

The Mirus is a highly experimental corvette that utilizes extremely advanced propulsion techniques, through use of a trans-dimensional "Spring" drive. The drive pushes space away, by accessing another dimension, nicknamed Spring, that directly affects ours. By pushing space in the Spring dimension, the craft is simultaneously pushed forward. This drive uses little energy, although it is somewhat volatile (no one knows how many test dummies are still in Spring). The true advantage of this drive is that it gives off no energy signature, due to the fact that all the thrust generated is in another dimension, and completely undetectable by sensors. This makes it the perfect stealth recon vessel.
EDIT: I've completely changed the backstory, added and updated ships, and planning on continuing. If you would like me to stop, please tell me to.
EDIT MK II: Added Mirus Corvette
EDIT MK III: Redesigned Ares, and created the Atlas Carrier