The fourth rate invites comparison with the 10-inch gun: both appear to occupy an attractive middle ground until rate of fire and striking power are compared. Guns above roughly 9.2 or 9.4 inches could approach the firing rate of 12- to 14-inch weapons while producing a smaller hit. The analogous ship problem was a hull too weak for the battle line and too expensive to buy in the numbers required for frigate duties. Its survival depended on narrower roles where an intermediate ship created a useful operational problem for an enemy. First World War scout cruisers and destroyer leaders filled a similar niche, using their extra size to act as flagships for smaller vessels rather than as conventional cruisers.
Chapter · 0:14-3:02
Why fourth rates struggled in the middle ground
Fourth rates sat awkwardly between ships of the line and cruising frigates, without enough fighting power for one role or affordable numbers for the other.