Peshtigo Fire Fatalities 1500–2500 (estimated)Chicago ~300
Occurring on the same day as the more famous Great Chicago Fire, the Peshtigo Fire has been largely forgotten.[3][4] On the same day as the Peshtigo and Chicago fires, Holland and Manistee, Michigan (across Lake Michigan from Peshtigo), and Port Huron at the southern end of Lake Huron also had major fires, leading to various theories of mutual cause by contemporaries and later historians.
https://en.wikipedia.org/wiki/Peshtigo_Fire
Comet theory
One speculation, first suggested in 1883, is that the occurrence of the Peshtigo and Chicago fires on the same day was not just a coincidence, but that all the major fires that occurred in Illinois, Michigan and Wisconsin on that day were caused by the impact of fragments from Comet Biela. This theory was revived in a 1985 book[18][19] and investigated in a 2004 paper to the American Institute of Aeronautics and Astronautics