Complex sentence: Francis and the rest of the Farewell family then moved from Holbrook to Tiverton, he became a Scholar at Blundell's School until the age of 13, when he left to become a Midshipman in the Royal Navy.
Split into simpler sentences: Francis and the rest of the Farewell family then moved from Holbrook to Tiverton. There he became a Scholar at Blundell's School until the age of 13, when he left to become a Midshipman in the Royal Navy.