I'd be curious about historical examples. My gut is that people come together and help each other for short-term disasters or where hope of help arriving is wi

I'd be curious about historical examples. My gut is that people come together and help each other for short-term disasters or where hope of help arriving is widespread (e.g. National Guard being mobilized, local disruption in a still functioning country). Past ~week, or shorter if there's no hope for things being fixed, people reasonably revert to survival.