Black Powder War (Temeraire Book 3) by Naomi Novik
Captain Laurence and Temeraire and their crew receive orders to proceed from China to Turkey to escort to Britain some Turkish dragon eggs that have been purchased by the British government. So they make the somewhat interesting, if slow, land voyage after engaging a mysterious guide.
They do meet some amusing feral dragons led by puffed-up braggart Arkady. Then they get to Turkey where they are imprisoned as “guests” and must cool their heels and send messages to the sultan.
Two of the younger members of the crew get in trouble by peeking in the sultan’s harem. Finally they uncover a conspiracy and make a dramatic escape with the eggs.
They manage to get to Germany where the Prussians are laboring to hold back Napoleon. The German commander has been waiting in vain for some British aid that never appeared, and he forces them to stay and help him fight rather than deliver the eggs on to Britain.
Here the book picks up tremendously as the French, advised by Lien (the treacherous Chinese dragon who became their enemy in Throne Of Jade), switch to tactics the Germans and their dragons have never before seen. Napoleon starts stomping the hell out of Germany, forcing huge retreats. There’s a siege and a daring and creative escape. A good read, if meandering in the beginning.