With the Revolutionary and Napoleonic Wars stretching the resources of the Royal Navy to their limit, the need for cheap ships to assume duties that would free up frigates for use elsewhere was soon readily apparent. This led to the commissioning of the Cruizer-class (model coming soon) and later Cherokee-class Brig-Sloops. While the Cruizer was the most-built ship design of the Napoleonic Wars, postwar construction would place the Cherokee as the most numerous design built by the British.
The vessels were armed with carronades which, thanks to their short length, could be given a greater calibre than a conventional cannon of the same weight. This meant that a small ship could put out the same broadside weight as a much larger conventionally-armed vessel, so long as she could close to within pistol shot distance.
It was therefore determined that Brig-Sloops would suffice for patrol duties, convoy escort and as mail packets, since the foe they were most likely to face, French privateers, would need to close-in to accomplish their goals and find themselves outmatched.
Unfortuantely, the origin of these ships as cost-saving measures really showed itself; they were too small for the global duties they were asked to assume, sank readily and came to be known as “coffin brigs.” A full quarter of these ships were lost.