Complex sentence: Born in Cobb County, Georgia, he moved to Atlanta at a young age and began as a volunteer fireman at the age of 15 and in 1872 at the age of 18, he was made assistant-chief the first of many promotions.
Split into simpler sentences: Born in Cobb County, Georgia, he moved to Atlanta at a young age and began as a volunteer fireman at the age of 15. In 1872, at the age of 18, he was made assistant chief, the first of many promotions.