Throne of Jade (Temeraire, Bk. 2)

Captain Will Laurence, formerly of His Majesty’s Navy, has had only a few months to adjust to his new life as the captain of a fighting dragon, but now he can't imagine a life outside the British Aerial Corps - nor a life without Temeraire. Now the Chinese have demanded Temeraire's immediate return, and the British government cannot afford to refuse them, even if it costs them the most powerful weapon in their arsenal. Laurence and Temeraire must journey to China, knowing that once they arrive in the exotic east, they could be separated forever.