Analyzing Metastable Failures in Distributed Systems (muratbuffalo.blogspot.com)

One major failure event of this type that had nationwide repercussions was the “St. Valentines Day massacre” of 1990 that brought down the entire AT&T POTS long distance telephone network for a day.

https://telephoneworld.org/landline-telephone-history/the-cr...

An amazing bug, when you consider it.