Complex sentence: On October 8,1871, when the Great Chicago Fire swept through the city, Horatio Spafford was a prominent lawyer in Chicago (1), and had invested heavily in the city's real estate, and the fire destroyed almost everything he owned.
Split into simpler sentences: On October 8,1871, the Great Chicago Fire swept through the city. Horatio was a prominent lawyer in Chicago (1), and had invested heavily in the city's real estate, and the fire destroyed almost everything he owned.