In one of my worlds I have a people who live almost exclusively on the surface of the ocean. Over their world's short history they quickly develop from the equivalent of island tribe tech to medieval and then, once they got access to lots of metal, most of their tech advanced to the equivalent of between 1920's to 1960's US/UK.
They have a highly stratified society which is a bit of a cross of a cast system and fiefdoms as well as quite a bit of small/local religions that all follow similar themes. They must trade with other, land-based, peoples, and gather resources from all over the ocean, transporting supplies between ships. It's a huge operation, but communication magic is extremely prevalent and easy to use; which also poses a problem.
The issue I am facing is what tactics can be used on ships, fleets, and city ships to keep order and control of the lower class when they can communicate so easily. Primarily, methods to keep them from taking over the ship and other industrial infrastructure. At the same time, I need a way that, probably due to failure to follow those methods properly, several thousand ships were taken by their lower class populous to form a nation of their own.
I've tried to look into mutinies, but haven't found much useful information there yet.
If it matters, spears, bows, and spear shaped guns are the norm for soldiers rather than swords and pistols, along with tall thin shields (usually just shorter than the intended user and about half their width). Oh, fire is everyone hated enemy and sinking ships is a HUGE taboo.
Thank you to any who can contribute.