From Battleship Protection to a Number on a Character Sheet
Naval war games need a compact way to represent why one ship is harder to damage than another. Instead of modeling every plate of armor and every impact in detail, rules can sort targets into armor classes—ratings that help determine whether an attack succeeds. Early Dungeons & Dragons carried that kind of classification into fantasy combat.
The important adaptation was the abstraction: a player could compare an attack with a target’s defensive rating and resolve the result with dice. A referee did not have to calculate how a sword met each piece of armor. The same basic idea could cover a heavily armored knight, a lightly protected thief, or a monster with a tough hide.
A Naval Idea, Recast for Adventure
The analogy has limits. A battleship’s armor and a person’s armor are not physically equivalent, and D&D’s rules were not a literal simulation of naval damage. The useful inheritance was a game-design shortcut: turn a complicated question—“How difficult is this target to hit?”—into a rating that can be used quickly at the table.
That older framework also helps explain why early D&D armor class worked in a direction that can feel counterintuitive to newcomers: lower numbers represented better defense. Later editions changed the scale, but kept the central job of the rating. A naval-style tool for classifying protected targets had become one of fantasy role-playing’s most recognizable mechanics.
