Complex sentence: In July, she began operations to capture Île de France, which culminated in the disastrous Battle of Grand Port where the British lost all four frigates, including "Magicienne" which ran aground and was scuttled by fire.
Split into simpler sentences: In July, she began operations to capture Île de France, which culminated in the disastrous Battle of Grand Port. In the battle, the British lost all four frigates, including "Magicienne" which ran aground and was scuttled by fire.