Murphy does a fine job of setting the scene for the dramatic events that began October 8, 1871. The Chicago before the Great Fire was a bustling, prospering city— a center for freighters sailing the Great Lakes and an important link for commerce between eastern and western North America.

It was built on a marsh, and consequently the streets were often muddy; the city had built elevated, wooden sidewalks so that pedestrians could avoid the ooze. That year, a drought had dried the sidewalks until they were ready tinder for fires. Also, the many big, proud buildings of central Chicago that appeared to be stone or concrete were actually mainly wooden—wooden facades had been carved and painted to resemble stone.

These, too, were very flammable.

There were a few buildings that had been constructed to be fire resistant, but these contained a deadly flaw. Murphy describes the...