The Great Chicago Fire was not one fire, but a succession of nine separate fires started by flying brands carried from earlier burning sites, which then melded into one relentless inferno. It all started in the O'Leary barn on a rear alley of DeKoven Street on the near West Side at 8:30 pm on October 8, 1871. Amid firefighting difficulties and official confusion the fire spread north and eastward. Ninety minutes later a burning brand, caught in the updraft, sailed over and landed on Bateham's Mills to the north, starting a second fire. Brands from there started other fires across the river near and in the business district, and by 2:30 am a flying brand started a fire on property north of the river. Given the prevailing winds, the coalescing fires burned most of the western portion of the city center and a swath of the North Side heading north-north-east to the lakefront by 6:00 am the following day. By then it was unstoppable. Over the next twenty-two hours the fire finished off the business district, lakefront harbor, and a large wedge of the North Side as far as Fullerton, by which time rain helped it burn itself out.

Author: Michael P. Conzen (Research assistance: Christopher P. Thale)
Source: Newberry Library