(Found) Generation ship, fleet with limited inter-ship contact, alien joins fleet

[tachyon]

OK I'm looking for a generation ship novel where there's a fleet of mostly independent ships that are moving together toward the destination (which I forget)

Each ship has evolved different cultures/governments and they don't fully trust each other, but still exchange info, resources, & visit between ships. POV characters are from one ship and the book follows their struggles to keep the ship running, maintain relations with other ships and complete the mission.

At some point in the past a war or battle may have been fought between some of the ships.
There are dead ships in the fleet that either no longer communicate or have failed and are actually lifeless.
At one point there's an expedition to another ship in the fleet.

Eventually one of the dead ships is discovered to be an alien that's tagging along. I think the POV ship mounts an expedition to this dead ship and takes care to try to keep the expedition secret from the other ships.

I feel like I read this in ebook in the last few years, but none of the titles on my kindle seem right.

Thanks in advance!

 

[chrispenycate]

Might this be Alastair Reynolds Chasm City? Not the prime plot (which involves Chasm City itself) but the secondary flashback plot (which would make it that much harder to find).

 

[tachyon]

@chrispenycate you've got it exactly right. I scrolled by Chasm City several times because I was thinking of the main plotline, thank you.