I've got a sci-fi novel in the works, and I'm not sure how I should start it off. Basically, the main plot of the story is set in motion long before the events of it occur. Here's a rundown of the plot; in 2190, it has been 130 years since humanity has successfully colonized other worlds out in space, and developed technology to the point where interstellar travel is practical, rather than merely possible. In that time, they've come across and allied themselves with (though not joined with) a semi-galactic coaliton of species and governments united with the cause of securing peace and stability throughout the galaxy, whom I'm currently calling the Federation until I'm inspired to come up with something more original. However, the coaltion isn't the only group out in space, and one of them, a single-species empire, with the species heavily resembling bipedal lizards I'm currently naming the dragonians, that is run by a belligerent, dictatorial government, happens to have close borders with human territory - territory that is rapidly expanding. Inevitably, a human patrol group runs into a dragonian patrol group out in space, and an ensuing battle nearly decimates both groups, who then flee back into their respective territories. [This event right here, is one of the scenes where I could start my story.] The response from the human population is that of widespread panic, fueled greatly by a declaration of war from the dragonian empire shortly after the incident. As their military forces begin mobilizing for war, their central government presents their case very openly to the rest of the galaxy, perhaps in a very biased light - a budding spacefaring civilization that was attacked without reason by a species hyper-focused on conquering the whole galaxy. In outrage, the Federation, and other groups who were adversaries with the dragonians, side with humanity to form a massive join-species fleet, and rush to the offensive. With more than half of the known galaxy turning against them, the dragonian empire is thrown into a state of complete disarray, and their military might is eventually decimated. Under the suspicion that the dragonians were building a planet-killer to turn the tide of the war, the join-fleet used that as an excuse to assault every single dragonian-owned planet. Whole worlds are outright abandoned as billions in total end up fleeing back to their homeworld, which quickly suffers from overcrowding, along with the severe side-effects of it. By the time the joint-fleet is amassed in orbit above the dragonian homeworld, their world is already in a state of near-apocalypse. Severe resource shortages, mass riots, even full-blown wars spring into being, and the ruling family formerly in charge of the empire slips into hiding amidst the chaos. The state of the planet itself degenerates from near-pristine into barely better than a giant junkyard. Long story short, the war is over, and humanity, since it was their war to begin with, is tasked with managing the now-leaderless species, and 'rehabilitating' them. Cut to 2784, six centuries after the war, and the dragonian homeworld has mostly returned to a healthy condition. The same can't be said for the species itself. On their homeworld, the dragonians' culture has been completely wiped out, and most of the planet's citizens find themselves in varying states of destitution. Many of them have a lifelong goal of simply being able to find a home off-world. The management of the homeworld has long fallen into the hands of a prominent mercenary group, who was more than willing to be tasked with it once the central human government decided their military should be more focused on other, more productive ventures. 'Management' has gradually become 'occupation under martial law' ever since. The other choice for a starting point for the story lies with the mercenary group's discovery of the descendants of the ruling family that once led the dragonians, and their subsequent classification of those descendants as threats. As teams of assassins are being readied to quietly exterminate the descending families, the decision catches the notice of the Federation's espionage network, and a private meeting is held between the leaders of the respective civilizations affiliated with the Federation [which is the other potential starting scene], where it is decided that the descendants of the ruling family, now no more than second-class citizens at best and clearly in no position to form a rebellion, were to be extracted offworld. After that, the story follows the perspective of the descendants who are fleeing from the assassins, and the special forces unit tasked with making sure they survive. Basically, should I start my story off with a war and jump to the main plot afterwards, or should I start off with the meeting that holds much more immediate relevance to the main conflict of the story (or at least fleshes it out much more clearly), while still providing exposition on the war through character dialog?