page_title: Great Chicago Fire
section_title: Precise start
hierarchical_section_title: Great Chicago Fire / Precise start
caption_attribution_description: English: illustration from Harper's 1871 depicting Mrs O'Leary with her cow.
context_page_description: The Great Chicago Fire was a conflagration that burned in the American city of Chicago during October 8–10, 1871. The fire killed approximately 300 people, destroyed roughly 3.3 square miles of the city, and left more than 100,000 residents homeless. The fire began in a neighborhood southwest of the city center. A long period of hot, dry, windy conditions, and the wooden construction prevalent in the city led to the conflagration. The fire leapt the south branch of the Chicago River and destroyed much of central Chicago and then leapt the main branch of the river, consuming the Near North Side.
  Help flowed to the city from near and far after the fire. The city government improved building codes to stop the rapid spread of future fires and rebuilt rapidly to those higher standards. A donation from the United Kingdom spurred the establishment of the Chicago Public Library, a free public library system, a contrast to the private, fee-for-membership libraries common before the fire.
context_section_description: Almost from the moment the fire broke out, various theories about its cause began to circulate. The most popular and enduring legend maintains that the fire began in the O'Leary barn as Mrs. O’Leary was milking her cow. The cow kicked over a lantern (or an oil lamp in some versions), setting fire to the barn. The O'Leary family denied this, stating that they were in bed before the fire started, but stories of the cow began to spread across the city. Catherine O'Leary seemed the perfect scapegoat: she was a poor, Irish Catholic immigrant. During the latter half of the 19th century, anti-Irish sentiment was strong throughout the United States and in Chicago. This was intensified as a result of the growing political power of the city's Irish population. Furthermore, the United States had been distrustful of Catholics (or papists, as they were often called) since its beginning, carrying over attitudes in England in the 17th century; as an Irish Catholic, Mrs. O'Leary was a target of both anti-Catholic and anti-Irish sentiment. This story was circulating in Chicago even before the flames had died out, and it was noted in the Chicago Tribune's first post-fire issue. In 1893 the reporter Michael Ahern retracted the "cow-and-lantern" story, admitting it was fabricated, but even his confession was unable to put the legend to rest. Although the O'Learys were never officially charged with starting the fire, the story became so engrained in local lore that Chicago's city council officially exonerated them—and the cow—in 1997.
  Amateur historian Richard Bales has suggested the fire started when Daniel "Pegleg" Sullivan, who first reported the fire, ignited hay in the barn while trying to steal milk. Part of Bales's evidence includes an account by Sullivan, who claimed in an inquiry before the Fire Department of Chicago on November 25, 1871, that he saw the fire coming through the side of the barn and ran across DeKoven Street to free the animals from the barn, one of which included a cow owned by Sullivan's mother. Bales's account does not have consensus. The Chicago Public Library staff criticized his account in their web page on the fire. Despite this, the Chicago city council was convinced of Bales's argument and stated that the actions of Sullivan on that day should be scrutinized after the O'Leary family was exonerated in 1997.
  Anthony DeBartolo reported evidence in two articles the Chicago Tribune (October 8, 1997, and March 3, 1998, reprinted in Hyde Park Media) suggesting that Louis M. Cohn may have started the fire during a craps game. According to Cohn, on the night of the fire, he was gambling in the O'Learys' barn with one of their sons and some other neighborhood boys. When Mrs. O'Leary came out to the barn to chase the gamblers away at around 9:00, they knocked over a lantern in their flight, although Cohn states that he paused long enough to scoop up the money. Following his death in 1942, Cohn bequeathed $35,000 which was assigned by his executors to the Medill School of Journalism at Northwestern University. The bequest was given to the school on September 28, 1944. The argument is not universally accepted.
  An alternative theory, first suggested in 1882 by Ignatius L. Donnelly in Ragnarok: The Age of Fire and Gravel, is that the fire was caused by a meteor shower. This was described as a "fringe theory" concerning Biela's Comet. At a 2004 conference of the Aerospace Corporation and the American Institute of Aeronautics and Astronautics, engineer and physicist Robert Wood suggested that the fire began when Biela's Comet broke up over the Midwest. That four large fires took place, all on the same day, all on the shores of Lake Michigan (see Related Events), suggests a common root cause. Eyewitnesses reported sighting spontaneous ignitions, lack of smoke, "balls of fire" falling from the sky, and blue flames. According to Wood, these accounts suggest that the fires were caused by the methane that is commonly found in comets. Meteorites are not known to start or spread fires and are cool to the touch after reaching the gr
caption: 1871 illustration from Harper's Magazine depicting Mrs. O'Leary milking the cow
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