By John Dodge

By John Dodge

CHICAGO (CBS) — Wednesday is the 143rd anniversary of the Great Chicago Fire. Here are five things you need to know:

1) The fire started around 9 p.m. on Oct. 8, 1871 and burned for two days, when it was finally fully extinguished by rain showers.

2) The fire did start behind the barn of Patrick and Catherine O’Leary just southwest of the city center. However, the cause of the fire is not officially known. The story that a cow started the fire by kicking over a lighted lantern in the barn has never been proven.

3) The fire spread north and east, and the center of the city was destroyed. At least 300 people were killed and 100,000 left homeless. (Click on image below to enlarge)

Courtesy of "Chicago and Its Makers" (Chicago: Felix Mendelsohn, 1929).

Courtesy of “Chicago and Its Makers” (Chicago: Felix Mendelsohn, 1929).

4) Firefighters were first sent to the wrong neighborhood, allowing the fire to spread out of control.

5) The disaster led to looting and lawlessness. Martial law was declared on Oct. 11 and troops descended on the city to restore order.

Sources: The Chicago History Museum, The History Channel