In the 18th and most of the 19th centuries, a
sloop-of-war in the Royal Navy was a
warship with a single gun deck that carried up to eighteen guns. As the
rating system covered all vessels with 20 guns and above, this meant that the term
sloop-of-war actually encompassed all the unrated combat vessels including the very small gun-
brigs and
cutters. In technical terms, even the more specialised
bomb vessels and
fireships were classed as sloops-of-war, and in practice these were actually employed in the sloop role when not carrying out their specialized functions.