We do not have a real identity as a 'species' per say - our kind is simply referred to as the "Collectors". For our organization's purpose is to preserve the works of art from across the galaxy in an archive spanning millions of artifacts from thousands of civilizations. We specifically are a newly made branch of collectors on our first task - to retrieve artifacts from a civilization before it is wiped from existence.
The civilization in question is one that is burned down to its last world, its home world. They had reached out to us earlier to preserve their cultural treasures, but only now have we mobilized the retrieval force.
We may have technological advantages in speed and maneuverability, but in raw warfare there is very little we can do to influence the unfortunate outcome of the Siege. Our vessels do not come unarmed, it is simply because the invaders have a whole fleet while we only have a ten ship brigade. Said outcome being the inevitable destruction of this world and its millennia of history. Calling for outside support is not our jurisdiction and it is not why we are here. This world made too many enemies and there is simply no galaxy wide organization dedicated to diplomatic affairs in the current epoch.
However it may just be possible to get artifacts - and ideally living members of the species off world fast enough that we do not get intercepted by the Siegers.
There is a several obstacles that make this hard.
The first obstacle is that there is no stealth in space.
The second obstacle is that there is no "warp drive" in our universe. Instead our universe has a network of jump points situated near stars that link to other stars.
The third obstacle is the formidable invading fleet that despite having little if any means of reinforcement, have managed to secure much of the star system.
The architecture of the star system is as follows. Each feature/world is labeled in order of distance from the parent star:
Star Count: One. G4.3-class
There is a vulcanite asteroid belt near the Roche-limit. Various patrols are located here. There is six jump points, most of which are well guarded. But only one jump point has the bulk of the invading force pouring in.
0.12 AU; Barren world with low eccentricity orbit. It is a hot planet with little atmosphere. This world is 3000 km in diameter. Tidally locked. There is not much activity here.
0.3 AU; Barren world that is 4300 km in diameter with slow rotation akin to Mercury. It is on this world that the Siegers have based themselves on after destroying the native mining facilities.
0.6 AU; A large world around 13000 km in size with a thick atmosphere. This world is not in a completely stable orbit. It's a hot world with volcanic activity and a small belt of asteroids that make a tenuous ring. Strip mining of this world has left many deep quarries all over the place. This world has few inhabitants and is not being prioritized by the invaders despite having some patrols in orbit. The invaders are focused on destroying the city world first.
0.9 AU; At 0.9 AU out is the world that is under siege. It is a city world about 7800 km in diameter with very developed defense systems, but these defense systems are taking a toll from repeated attempts by the invaders to irradiate entire continents in hit and run attacks. They have space elevators concentrated near the point of their world where tidal locking is most intense. The invaders intently keep watch on this area, but the high amounts of traffic around the world have made it hard for the invading force to know where exactly the defenders are building up which has allowed the defenders to set up more defenses with what time they have. The world is densely urbanized and they are aware of our mission. Communicating is not that difficult despite the blockades, but physical exchange is what our purpose is.
3 AU; a Jovian world 37000 km in diameter with two barren moons and a somewhat eccentric orbit. The distance of the world has not prevented it from being targeted by invading forces that bombed apart the infrastructure on the moons.
6 AU; A large icy world about 6000 km in diameter that is another hold out due to distance and a underground colony that is laden in defense systems. The invaders, like with the other hold out have put little effort into destroying this place yet.
12 AU; A dim small ice world further out around 5000 km in diameter. There's just robots here.
With this information, how can artifacts be retrieved from this world in a timely matter while minimizing the destruction of assets?
We have a around ten space craft entering from a jump point separate from the main jump point. The leading ship is a cruiser, the other nine are smaller more specialized ships used for rapid retrieval equipped with surface-orbit shuttles. Destroying the guards at the jump point is the easy part for us, the hard part is contending with the actually powerful spacecraft that are of true war making capability. Our spaceships have superior maneuverability to the invaders' designs, but our weaponry and defenses have only a slight advantage at best- and the invaders out number us by a factor is 20:1. Or 120 spacecraft. They are somewhat spread out, with the majority of their spaceships in orbit of the city world.
Technology wise our shielding can handle particle weapons (for a several minutes) but kinetic weaponry can overwhelm the defense systems. The invaders have both such weapons- as do we. The invaders also have WMDs designed to make habitable worlds uninhabitable for millions, if not billions of years. Thankfully the invaders don't really hate us as much as they hate the civilization they are trying to wipe out. But they do not want us being here either way, they do not want reminders of this society's existence floating about the galaxy and will target us for disregarding their 'wishes' so to speak.
Our spacecraft can manuver rapidly due to us being not exactly biological beings, unlike the invaders who are only partial cyborgs. So G-force problems are of less concern to us. Our ships can move at 0.09 c, while the invaders move only around 0.04 c. The invaders also accelerate slower than we can.
If you believe we should acquire certain technologies (stealth systems are not available) or allocate more resources into this venture, please specify. es into this venture, please specify.