Complex sentence: While Ottavio's position had been given as a means to strengthen the family position, and came with strings, his military success later bred resentment and he began to see himself as a commander unaccountable to his family ties in Rome.
Split into simpler sentences: While Ottavio's position had been given as a means to strengthen the family position, the piosition came with strings. His military success later bred resentment as he began to see himself as a commander unaccountable to family ties in Rome.