Complex sentence: Despite being told by one of his officers that the mess staff had eaten the fruit, Queeg insists otherwise and proudly tells Maryk and Keefer that as an ensign he was commended for unmasking a cheese thief.
Split into simpler sentences: Despite being told by one of his officers that the mess staff had eaten the fruit, Queeg insists on believing otherwise. He relates a story to Maryk and Keefer of when he, as an ensign, was commended for unmasking a cheese thief.