Pirate hunter
Once they were not necessary anymore, but today they are back.
A Pirate hunter is a person, or a crew, possibly with a ship, dedicated to finding pirates and bringing them to justice, dead or alive. Often skilled in naval warfare, espionage, and several forms of kidnapping to practise their trade.
Age of Sail
During the age-of-sail there where quite a lot of Pirate Hunters, working under a similar system as Privateers did with a Letter of marque, or other simularly funcitoning license or wanted poster from a government. As for a government it was much cheaper to hire a private person or organisation, and let them keep a part of the pirates treasure, then to send out their navy. And for hunting individual pirates this was a reasonable option. When pirating got out hand then the navies of the world had to act and they did that so rigorously that they wiped out most of the pirates of the world. This made the job of Pirate hunter basically obsolete.
Safe seas
For ages the world's navies policed the seven seas, and with the exception of some local hot spots of sea-born burglary the seas where safe from piracy, and ships could go about their way free and happy. Trade in all corners the globe and make profit everywhere. Cannon disappeared from merchant ships, and later also the pistol left the Captain's fault, it was not necessary anymore.
Pirates are back
But slowly pirates crawled back in to world, from the dark corners where evil resides they stepped closer to the light. What started as rumours among ship's crews slowly got known in the ship owners office, and from there the got to the back rooms of politicians. But merchant ships where not deemed important enough to get votes. So pirates slowly got more bold.
Until the day came that they turned from robbing the crew and emptying the captains safe, to kidnapping the crew for high ransoms. Then the ship owners couldn't pretend it didn't happen anymore, and when the journalists got wind of what was happening neither could the politicians.
So the navy got turned back to their old job, protect the nations shipping interest. But they found themselves very under equipped to take up this core job, and it was very expensive, which the governments tried to turn on the ship owners. Who'm quickly turned elsewhere, where it was cheaper. So the Pirate hunters, where back.
The knights of Rhodes are a catholic order with origin with the Knights Hospitaler, they started their existence while fighting the Barbery pirates in the 15th Century. For a long time they had their own fleet of naval ships, and worked as guards on private owned ships, or assisted navy ships.
With the demise of the pirate, they also dwindled in existence, as they had no purpose. But the order remained, small but remained. And most recently they built four ships of the Saint George of Lydda class to go out and actively hunt pirates again. First they focused on the Somalia pirate issue, but lately they've been getting reports of a pirate operating in the Caribbean and Gulf of Mexico.
I really like that it was rendered obsolete, but now it's becoming necessary again.
Thank you