Fourth rates multiplied deterrence on foreign stations

Fourth rates made particular sense in shallow Baltic waters and on distant stations where presence mattered as much as fleet combat. East Indiamen could resemble them closely enough to make a raiding squadron hesitate, while a real fourth rate could overpower a frigate or add another fighting hull to a battle line. Their crews were slightly smaller than those of third rates, giving the Navy extra deployable hulls that could still reinforce the battle fleet when needed. This uncertainty acted as a strategic force multiplier because the enemy had to account for a threat out of proportion to the small number of ships purchased. Q-ships and later convoy defence worked on a similar principle: publicity about 4-inch guns aboard merchantmen discouraged German submarines from running through a convoy's centre even when the actual fit varied. In both cases, uncertainty changed enemy tactics before every concealed weapon had to be used.