The Fortune of War, by Patrick O'Brian, is very different from the previous books.W hile several have had stretches set on land, in this book Aubrey is never in command of a ship after the first chapter or so.
After sailing the battered Leopard into harbor in the Dutch East Indies, Aubrey takes the first ship out to England, along with Maturin and the other followers. after various catastrophe's, they end up on a different ship, the Java, which ends up loosing a battle to an America man-o-war. Jack is seriously injured and Stephen goes with him to Boston, where they wait to be exchanged. When Diana Villiers arrives in town with Henry Johnson and Louisa Wogan, American spies, Stephen is in great danger.
The characters of Jack Aubrey and Stephen Maturin have almost become your friends by this point in the series. I worry about them! I was so sad for Stephen when he lost the vast collection he'd accumulated in the time on Desolation Island. I was anxious for Jack when he was injured. That is great writing when you know there are another 15 books in the series with these characters and you are still so concerned in the moment that you are not sure they will make it! a 6!