Complex sentence: Orphanhood was not the only vicissitude that visited La Martinière's childhood.At the age of twelve, he was taken captive by the Barbary corsairs only to be liberated by the Knights of Malta at the age of sixteen.
Split into simpler sentences: Orphanhood was not the only vicissitude that visited La Martinière's childhood. He was eventually liberated by the Knights of Malta at the age of sixteen.