When attacked by Lyons the city completely disappears. Similarly, on an earlier turn, when Lyons attacked Ft. Wayne, it completely disappeared as well.
Not good!
AMD Phenom II X4 965; 8GB; Radeon HD 5670 cat. 13.9 drivers; win 7 updates current.
Uninstalled/reinstalled/updated-> replayed previous turn-> problem gone (i.e. Fayette is still there; Ft. Wayne is still missing, but that was an even earlier turn)... no idea....
When a level 1 city or a settlement autoraises a garrison and looses the battle, there is a small chance that it will be destroyed during the battle (Level 1 cities are considered small enough to be razed during the battle if the townspeople took up their guns and defended it via automilitia garrisson). If the razed city is above level 1, then we have a bug. I think the dev team is currently working on it.