Complex sentence: During four months of raids Iberville was responsible for the destruction of thirty-six Newfoundland settlements and by the end of March 1697, only Bonavista and Carbonear Island remained in English hands.
Split into simpler sentences: During four months of raids, Iberville was responsible for the destruction of thirty-six Newfoundland settlements. By the end of March 1697, only Bonavista and Carbonear Island remained in English hands.