This is the one with the Chairmaker. If you have read it, that’s probably all you need to know. That made me go brr, just writing it.
It’s about a solider of fortune, who goes from place to place, winning wars, or losing wars, depending on what he’s asked to do by the Culture. Although he’s not of the Culture. Anyway, the story is about what motivates him to fight, because the Culture wants him to come out of retirement for one more war. But the payment is that he wants to go right back to the very beginning, where he was pulled out of the snow after the thing with the chair.
It’s very nicely structured, with one set of chapters going forward and one going backwards; starting at different points. Each war has different protagonists, with different weapons, and the descriptions of those are all very entertaining. There’s also some insight into why the Culture wants one thing or another – this is the work of an author really finding his world.
And the chair.