Heavy American frigates still faced a two-deck disadvantage

The largest American frigates were not straightforward fourth-rate equivalents in combat. The United States lacked ships of the line to support them because of congressional choices. A genuine fourth rate's two complete gun decks provided height and concentrated firepower, allowing it to fire down into a frigate while bringing more guns onto the same angle. The Chesapeake-Leopard affair illustrates the resulting coercive advantage: even a capable American frigate had sound reasons to avoid a fight whose paper odds understated the physical disparity.