Original sentence: At 16 he joined the Marines and four months later found himself fighting the Japanese at the Battle of Okinawa.When he was 15 the farm burned down and, while still in his teens, he went to work in the coal mines and later in the steel mills of Pennsylvania
Edited sentence: A month before his seventeenth birthday he joined the Marines and four months later found himself fighting the Japanese at the Battle of Okinawa.When he was 15 years old the farmhouse burned down and he went to work in the coal mines and later in the steel mills of Pennsylvania