What do space empires fight over?

[Maxperson]

War machines also make a lot of people rich and/or powerful. Often wars are started to support the wealthy and/or corporations make more wealth.

 

[DeviousQuail]

Expansion into currently unclaimed territory.
The rise of a separatist force along the borders of two or more empires.
Solar system destroying technology being tested on another empire's territory.
Anything in the Foundation series by Aasimov.
An alien species that brought many empires to their knees before it was eradicated is found alive and being nurtured by one empire (Rachni or Krogan from Mass Effect).
Space locusts.
A long disappeared mega empire returns and wants its space back.
One empire's financial/religious/etc control over another becomes too much.

 

[Tilt]

Ancient artifacts, like in The Expanse. Things of power left by an ancient civilization.

 

[ccs]

Nobody actually remembers.
Oh sure, talk to 100 people & you'll get at least 100 reasons, reasons will vary depending upon where you are, and some will be more plausible than others, but.... No one truly knows anymore.

 

[billd91]

Yeah, it comes down to religion, politics, traditions - the fun stuff.

Traveller did this with some of their races, partly dependent on native psychology, but could be translated into cultural values. The examples I’m thinking of are the Aslan and Vargr. Both do involve territory, but neither simply because they need space. The Aslan are landed clans but second (and later) sons don’t inherit the clan lands so they are driven to take and settle their own. Resources aren’t an issue, inheritance and ownership are. The Vargr are at least partly judged by their rep, their prestige, their charisma. Ambitious warlords will grow their charisma by raiding or even taking worlds. So again, not actually about the space, but about the person taking the space.

For politics, there’s the idea of balance, denying another empire systems to keep them from growing or encroaching your space. Maybe the wars are to set up or protect client states as buffers (like the xth Frontier Wars in Traveller between the Third Imperium and the Zhodani Consulate.

 

[Argyle King]

This is a world building question. What’s the conflict?

So if you have a galaxy full of space empires. Say a dozen at least, each covering a big swathe of the galaxy. And you assume that:

1) space/habitable places isn’t an issue. Space is big and they’re not short of land.
2) a single resource like Dune’s spice or Discovery’s dilithium is a well-mined trope you want to avoid.
3) you want to steer clear of “species” othering: assume they’re all human and have similar motives.

How do you create constant conflict between these space empires? If indeed you can after ruling out the above?

Assuming that everyone has enough land and resources to not need more, as well as a group of people who all have similar views and motives, I think most conflicts would come down to petty and personal reasons between rulers.

Space Greece sends a thousand starships to right the wrong of Space Troy's prince stealing somebody's wife. The soldiers are convinced that an affront to their ruler (who is the embodiment of their culture and the face of their society) is an insult to them (or perhaps the opportunity to get educational benefits for galactic college was attractive).

You may be able to get some motivation from Twitter, YouTube, rap beefs, and how the fans/followers of various celebrities fight with each other based upon their emotional investment in the conflicts between the celebrities themselves. In some cases, it doesn't even matter that two sides have virtually identical beliefs; it's enough that they self-identify as being in conflict with the other groups based upon superficial reasons (i.e. red vs blue; XBox vs Playstation; Coke vs Pepsi).

 

[Khelon Testudo]

Even for a post-scarcity society, some projects are so big that they may require more resources than they have to hand. Building a dyson sphere around the black hole in the centre of the galaxy - maybe to generate energy?

 

[Dioltach]

The view: the night skies in some parts of the galaxy are just to die for!

 

[tomBitonti]

A group might, despite the availability of space, just like taking other folks stuff, rather than making the stuff for themselves. Or, other similar creatures might be raw resources, as in Jupiter Ascending. Or, a civilization or race may be inherently warlike, for example, 40K orcs, or Saberhagen’s Berserkers. Or, war might be used to stabilize a political order. Or as a way to realize warrior or spiritual ideals. Or might be instigated for entertainment, or cruelty, or to destabilize one or more civilizations, perhaps to prevent further advancement. Or one civilization might find another‘s practices morally appalling.

Be safe and well,
‘Tom Bitonti

 

[Bawylie]

1.) Entangled alliances and obligations
2.) Sport / Glory
3.) Conquest as evidence of might
4.) Perceived heresy between two or more very similar empires over a very slight difference of orthodoxy (doesn’t have to be religious)
5.) Honor impugned / honor redressed
6.) An old grudge simmers over
7.) The stars align such that one group interprets a providence or omen and decides to act on it
8.) Lies and deceit
9.) Incompetence (no one knows why Empire A attacked, could be as simple as someone breaking ranks and firing when they shouldn’t have, but once it started there was no turning back)
10.) Corruption and coverup
11.) Coercion and blackmail
12.) Love unrequited / forbidden / requited but otherwise obligated or unavailable
13.) For the Greater Good
14.) For Unity / Order
15.) To forestall doom
16.) To keep the people at home United against a common foe
17.) To win an upcoming election or keep a position
18.) To accelerate decline