Complex sentence: Napoleon was more impressed with Childeric's bees: looking for a heraldic symbol to trump the Bourbon fleur-de-lys, he settled on Childeric's bees as symbols of the French Empire.
Split into simpler sentences: Napoleon was more impressed with Childeric's bees when he was looking for a heraldic symbol to trump the Bourbon fleur-de-lys. He settled on Childeric's bees as symbols of the French Empire.