The Loss of the Burying Ground, by J Anderson Coats

Dura and Ariminthia have been at war for ages, each side convinced that they are right and neither prepared for peace.  But despite strong factions who want the war to continue and a hefty propaganda effort to promote the war, a fragile peace treaty has been drafted.  To sign it, the two sides agree to sail out into neutral waters on a ship called the Burial Ground with the entire leadership of both states on board. When the ship is destroyed in a freak storm and nearly everyone is lost, the chance of peace is put in jeopardy.

Two survivors -- Cora from Dura and a Ariminthian servant named Vivienne -- are washed ashore on a desert island.  After a lifetime of indoctrination, there is little trust between them.  But when pirates come ashore and threaten them, the two girls learn to cooperate for survival.  That buys them some time, but bigger challenges await these uneasy allies as they discover that the true nature of the conflict is far more complicated than they have been raised to understand.

A fascinating novel that explores the role of violence in politics and the impact of propaganda.  There's a lot to chew on here.  Perhaps a bit too much.  Things get rushed at the end and while we're being set up for a sequel or two, the care that was taken through the story to explain the competing interests gets muddied and rushed as events unfurl.

There's a human story as well about the two girls learning to see beyond their prejudices. Sadly, those human elements get lost in the end as Coats tries to tie up far too many loose ends.