TIL about "The Great Epizootic of 1872", a massive outbreak of equine influenza. Boston suffered a major downtown fire in part because firemen had to pull the equipment by hand instead of using horses, as they were all incapacitated by the epidemic.

That outbreak was like the viral equivalent of an EMP...

https://www.mentalfloss.com/article/65528/1872-equine-influenza-epidemic-sickened-most-us-horses

"Because horses were the lifeblood of transportation at the time, the economic impact was enormous. In an 1873 report for the American Public Health Association, Dr. Adoniram Judson collected anecdotes from around the country. He described reports of mail, groceries, and other freight sitting at docks, undelivered. Trains were idled because coal to power them was transported from mines to rail yards by horses. Physicians couldn’t reach their patients. Much of Boston burned as the fire wagons, pulled by men instead of horses, were unable to keep up with the fires that eventually destroyed 776 buildings in November of 1872. U.S. cavalry and the Apache Indians fought each other on foot, as horses on both sides were too sick to be ridden into battle."

/r/todayilearned Thread Link - en.wikipedia.org