As the novel begins, William Laurence is gaoled aboard , imprisoned against Temeraire's good behavior. Whilst aboardship, he joins the crew in fighting off the Grande Armée, who supported by the Armée d'Air are attempting to invade Great Britain. They succeed, and Laurence is reported to have been killed in action when "Goliath" is sunk. Temeraire, languishing at the breeding grounds at Pen y Fan, receives this intelligence and loses any desire to remain quiet and well-behaved. Instead, fired partially by patriotism and partially by vengeance, he organizes the many unharnessed dragons of the breeding ground into a militia, using promises of prizes as an enticement. Enlisting the breeding grounds' (human) supervisory staff as logistical support, he and the other dragons strike south to do what they can against Napoleon Bonaparte. This, of course, results in a merry chase: Laurence, who did not perish aboard "Goliath", is mustered by Tharkay, now commissioned in the Aerial Corps, to bring Temeraire back under harness, and he arrives at Pen y Fan perhaps half a day after the dragons move out. The two are reunited outside of Harlesden, where Temeraire has already staged and won a decisive victory against a group of Marshal Lefebvre; in fact, Laurence is intercepted by a courier who is seeking out the commander of the militia (that is, Temeraire) with a colonel's commission.