I picked up a book a long time ago in a library and I want to read it now, but I can't remember the name. It's about WWI except the US/UK use genetically modified animals to fight, while Germany/Austria uses steampunk machines. I think it also had pictures and involved a Prince of some kind.
This is The Leviathan Trilogy by Scott Westerfield.
Prince Aleksander, would-be heir to the Austro-Hungarian throne, is on the run. His own people have turned on him. His title is worthless. All he has is a battletorn war machine and a loyal crew of men.
Deryn Sharp is a commoner, disguised as a boy in the British Air Service. She's a brilliant airman. But her secret is in constant danger of being discovered.
With World War I brewing, Alek and Deryn's paths cross in the most unexpected way…taking them on a fantastical, around-the-world adventure that will change both their lives forever.
Young adult fiction set in alternate World War I has German Central Powers (Clankers) using mechanized war machines opposed by British Entente Powers (Darwinists) who fabricate living creatures genetically. Heroes are teens Aleksander, son of Archduke Franz Ferdinand, and Deryn, Scottish girl with dreams of joining the British Air Service with her brother.