Crucible of Gold - Naomi Novik

Crucible of Gold is the 7th novel in the Temeraire series.

Temeraire and Capt. Laurence have started to settle in Australia when the British come to their senses. They finally realize their only Celestial and his captain are needed in the war. They're reinstated with full rank and position on the captains list. The pair are head for Brazil to see if they can negotiate with the Tswana. Ship wrecks and other disasters cause the party to detour through the Aztec nation. The Aztec's consider that dragons are the masters and the humans the slaves. Adventures and danger haunt Temeraire and Laurence through the whole story. Very highly recommended.