Man of War by Alexander Kent

The setting is the West Indies, with the post-Napoleonic "revolution" against the ban on slavery. The navy is stretched to the limit, ships laid up, appointments for captains and senior officers hard to obtain. There's a lot of rivalry, as well as the discomfort of working with ships and sailors who have only recently been deadly enemies. Adam and the Unrivalled are in the thick of it.

A highly detailed study of the closest friends and most trusted commanders of Alexander the Great - their career-progress, rivalry with one another, their influence on Alexander.