Complex sentence: The older man's companions beat d'Artagnan unconscious with a pot and a metal tong that breaks his sword; his letter of introduction to Monsieur de Tréville, the commander of the Musketeers, is stolen.
Split into simpler sentences: The older man's companions beat d'Artagnan unconscious with a pot and a metal tong that breaks his sword. His letter of introduction to Monsieur de Tréville, the commander of the Musketeers, is stolen.