The nation slowly rose from the 'ashes' of war. = It slowly rose out of the 'ashes' and began to rebuild itself.
The city was reduced to 'ashes' by the fire. = The city was burned to 'ashes'.
Their happiness turned to 'ashes'. [=their happiness was destroyed]
(..) mourning the dead... Mother, father, and all our children? - Cersei... - I loved them. I did. But they're ashes now and we're still flesh and blood. We're the last Lannisters, the last ones who count. Even Lannisters can't survive without allies. (..)2017 TvShow: Game of Thrones Title: Dragonstone Season: 7 Episode 1