Symbolism, Imagery, Allegory
Part of the Latin motto of the Hapsburg family, Dr. Barlow says bella gerant alii to Alek to trick him into confirming her suspicions about his identity. Alek later explains to Deryn:
"It's called Latin, you simpleton. Bella gerant alli means 'Let others wage war.' She was saying we don't have to fight each other." (25.105)
This idea becomes important as Alek's crew and the people of the Leviathan realize they don't have to be at war just because their countries are. Instead, they are able to create a mutually beneficial, if cautious, alliance. Looks like the influence of the Hapsburgs crosses borders.