According to popular legend, the fire broke out after a cow – belonging to Mrs. Catherine O'Leary – kicked over a lamp, setting first the barn, then the whole city on fire. Chances are you've heard some version of this story yourself; people have been blaming the Great Chicago Fire on the cow and Mrs. O'Leary, for more than 130 years. But important research by Chicago historian Robert Cromie has helped to debunk this version of events.

An Old Cow's Tale
Like any good story, the "case of the cow" has some truth to it. The great fire almost certainly started near the barn where Mrs. O'Leary kept her five milking cows. But there is no proof that O'Leary was in the barn when the fire broke out – or that a jumpy cow sparked the blaze. Mrs. O'Leary herself swore that she'd been in bed early that night, and that the cows were also tucked in for the evening.

But if a cow wasn't to blame for the huge fire, who was? Over the years, journalists and historians have offered plenty of theories. Some blamed the blaze on a couple of neighborhood boys who were near the barn sneaking cigarettes. Others believed that a neighbor of the O'Leary's may have started the fire. Some people have speculated that a fiery meteorite may have fallen to earth on October 8, starting several fires that day – in Michigan and Wisconsin, as well as in Chicago.

The Biggest Blaze
While the Great Chicago Fire – and its "cow culprit" – was the best known blaze to erupt during this fiery two-day stretch, it wasn't the biggest. That distinction goes to the Peshtigo Fire, the most devastating forest fire in American history. The fire roared through Northeast Wisconsin, burning down 16 towns, killing 1200 people, and scorching 1.2 million acres before it was done.

Historical accounts of the fire say that the blaze began when several railroad workers clearing land for tracks unintentionally started a brush fire. Before long, the fast-moving flames were whipping through the area "like a tornado," survivors said. It was the small town of Peshtigo, Wisconsin that suffered the worst damage. Within an hour, the entire town had been destroyed, and some 800 residents lost their lives.

Remembering Safety
Those who survived the Chicago and Peshtigo fires never forgot what they'd been through; both blazes produced countless tales of bravery and heroism. But the fires also changed the way that firefighters and public officials thought about fire safety. On the 40th anniversary of the Great Chicago Fire, the Fire Marshals' Association of North America (now known as the International Fire Marshal's Association), the oldest membership section of the National Fire Protection Association (NFPA), decided that the 40th anniversary of the Great Chicago Fire should be observed not with festivities, but in a way that would keep the public informed about the importance of fire prevention.