Everything you need to understand or teach The Great Fire by Jim Murphy.
On October 8, 1871, on a lazy Sunday, a fire broke out in a barn near the edge of Chicago. According to Murphy, no one knows for certain how the fire started. He refutes the popular myth that it began when a cow being milked by Catherine O'Leary kicked over a gas lamp, saying that it was impossible for O'Leary to have been in the barn at the time.
At that time, Chicago was in the midst of a long drought, making its wooden buildings and wooden sidewalks very dry and thus vulnerable to fire. The city had already experienced a number of relatively small fires, including an especially troublesome one that the fire department had extinguished the previous day near the neighborhood of the O'Learys. Still, the fire department was well organized and well equipped, and it had been extinguishing fires with a high degree of success. Even so...