To use an apt term, it was a state of anarchy. The undead who usually maintained order, all ceased functioning overnight. Without anyone commanding them, they simply lay dormant in the cemetery.
In some places, another kind of power would help maintain order alongside the undead. But in places without that 'other' power, the whole system would continue to run inertially for a while until running into a blockade it could not overcome, leading to a quick collapse.
Rapids Fortress was in just such a situation.
The blockade that led to Rapids Fortress's collapse was food. Like many cities built on mountains, it wasn't a food production site. Similar to Northern Wind City, a large proportion of their food had to be transported in.
With the collapse of order, the inflow of outside food sharply decreased, and the prices also surged. Even if prices were increased, there were hardly any goods available to buy.
