On Sunday, October 8th of 1871, the Great Chicago Fire was started by accident.
The fire destroyed 3.3 square miles of the city of Chicago, and killed as many as 300 people. About a hundred thousand more people were left homeless.
The fire had started at about 9pm, in a small barn belonging to the O'Leary family. The story goes that the fire started when Mrs. O'Leary's cow kicked over a lantern, but no one really knows how the fire got started.
However, we do know how the fire spread. The Great Chicago Fire was fueled by the city's wood framed architecture, topped with highly flammable shingle roofs. Even the city's roads and sidewalks were made of wood at that time. Adding to the severity of the catastrophe was the unusually dry weather and strong southwest winds. It was a deadly combination of factors.
In 1871, the Chicago fire department consisted of only 185 overworked firefighters on the job, with just 17 horse drawn steam engines to assist them in protecting the whole city of Chicago. What's more, the firefighters were directed to the wrong location during the Great Fire. This gave the fire time to spread.
Firefighters kept trying to fight the fire, but eventually, the water mains dried up and left the city helpless. Firefighters hoped the river area would create a natural firebreak. However, the river was loaded with warehouses, coal yards and barges, so the fire made its way across the river, consuming everything in its path.
Mayor Roswell B. Mason began sending messages to other towns for help, but when the courthouse caught fire, he ordered it evacuated and ordered the prisoners being held in the basement to be freed. A short while later, the cupola of the courthouse collapsed, and the giant bell came crashing to earth. People said they could hear it from a mile away.
Across the river, the fire grew, as the southwest wind intensified and became super-heated. When hot air rises and mixes with the cold air above it, it creates what amounts to a tornado made of fire, also known as a fire whirl, throwing sparking embers in all directions. Flaming debris flew across the river and set fire to the buildings on the other side. All anyone could do was watch it happen.
Early on Tuesday of October 10th, it finally started to rain in Chicago, but the fire had already pretty much extinguished itself by then. There was very little left to burn.
At the end of it all, the Great Chicago Fire had destroyed an area about four miles long and averaging ¾ of a mile wide. It encompassed an area of more than 2,000 acres. About a third of the city's residents were left homeless. There were 120 bodies recovered, but the death toll may have been much higher. The fire also caused the destruction of 73 miles of roads, 120 miles of sidewalks, about 2,000 lampposts, and roughly 17,500 buildings, totaling (in today's dollars) more than 4 billion dollars in property damage, or a third of what the entire city of Chicago is worth.