Complex sentence: The Lane family's mill was destroyed in a fire and his parents opened a general store following the catastrophe, and it was there that Harry began his employment career at the age of 13, working part time as a clerk.
Split into simpler sentences: The Lane family's mill was destroyed in a fire and his parents opened a general store following the catastrophe. It was there that Harry began his employment career at the age of 13, working part time as a clerk.