On the surface of the planet Arconia, the capital of the Celestial Federation three girls are wreaking havoc among the planet's defense guard. One has long flowing silver hair with black eyes, she's wearing a white trench coat with a black armored vest underneath. She swings her golden blade and cuts a tank completely in half. Then jumping over the tank she slices a missile fired at her before swiftly extending her hand to create a magic circle that creates a rain of fireballs, engulfing the mechanized infantry that were accompanying the tank. 

The second woman also has silver hair but tied in a ponytail, her purple eyes squints at distant targets as she aims her large rifle and squeezes the trigger. An enemy commander a couple miles away has his head popped. She holsters her rifle over her back and draws a pair of revolvers from her black and white jumpsuit and rapidly drops a squad of special forces sent to eliminate her. Storing her revolvers back in their holsters she pulls out her rifle yet again and flicks a switch on the side, then aiming her rifle at an incoming gunship she fires a massive beam of energy that destroys the gunship completely. 

The third woman has short black hair and red eyes, her rather pale skin and slightly short stature may scare anyone not expecting her. It doesn't help that her father has thoroughly trained her in the art of stealth, and the fact that she's wearing a black armored suit designed to completely camouflage her with active camo and other stealth tech. She slits the throat of the commander of the orbital defense weapons command post, then she drew her suppressed pistol and eliminates the remaining crew. Afterwards she disables the defense system and plants explosives around the consoles, she then teleports out and blows up the controls. 

The girls gather on the top of a massive pile of rubble that used to be the presidential palace of the Celestial Federation. These girls are the princesses of the empire, Anna the first, Yvonne the third, and Ekaterina the forth. Anna comments on the chaos and destruction. 

-Yawns So girls, you think that's all of 'em? 

-Negative, i spot a second tank column to the east approximately 300 meters from our position. 

-I've confirmed Yvonne's intel, the data i collected from the defense system showed enemy reinforcements approaching. 

-Huh, i didn't expect them to so possessive over their capital. I thought they'd start withdrawing once we nuked the palace. 

-Possibility, they wish to kill or capture us to negotiate. 

-I agree, i don't think they would want to waste this many resources on the capital. There are far more strategically important locations to defend. 

-Ha! I'd like to see them try! C'mon girls, let's show these idiots the empire's true might! 

The girls scatter and Anna contacts the imperial fleets flagship up in orbit currently bombarding the military bases on the planets moon. 

-Hey November. 

-yeah, what is it Anna? 

-Gonna need you to stop the bombing on the enemies converging on the capital, send 'em else where. 

-Why? That's nearly half a million troops we got pinned with our bombers. 

-Terror, those idiots think they could capture us to negotiate. I wanna teach 'em a lesson. 

-Very well. But don't say I'd didn't warn you when you start feeling tired or bored half way through the slaughter. 

-Bah don't worry about it! Yvonne and Ekaterina are pumped up. 

-In that case my worries are unfounded. Good luck. 

-Thanks, though we won't need it. 

The space battle was just as one sided as the battle in the capital, the Federation's navy were annihilated during the early days of the empire's invasion. The remainder of the navy gathered by the capital star system in a desperate attempt to make a last stand and to very least blunt their advance. When the Federation's ships encountered the imperial fleet it wasn't the grand flotilla hellbent on conquering them, it was squads of destroyers and cruisers aided by carriers with their fighters and other strikecraft. The admirals wondered where the battle ships and frigates where? No matter, they had their hands full with the rapid maneuvers of the destroyers and cruisers. 

About a half hour later into the battle multiple ships were detected on the Federation's sensors, it was the empires battleships jumping into the fray. The battleships rammed into the the rear of the Federation fleet, ships were torn to shreds by the battleships massive rams. The frigates cut off anyone trying to escape and took out the defense systems and space stations on the perimeter of the solar system. This encirclement tactic was devised by the fleets commanding officer, vice admiral November Vortigaunt. With the plan to distract the Federation and encircle them with the battleships she impressed even her father on her on the spot thinking. 

With the complete destruction of its navy the Federation had no way of defending itself from orbital bombardment, the imperial fleet split up to eliminate any remainder of the Federation navy and capture strategic planets and other star systems near by, they didn't want reinforcements from the edges of Federation space to try and relieve the capital. Soon enough the capital fell and nearly all Federation troops either surrendered or were killed, interestingly a few managed to escape. Specifically troops and men who saw the horror that was the slaughter of 500,000 soldiers against 3 daughters of the empire. Recordings and testimonies quickly spread through the the remnants of the Federation, planets and troops surrendered without a fight when they heard the daughters were coming. Within 4 months the Federation was completely conquered by the empire, and within a decade it would be completely integrated into the empire's fold.