Perhaps to many readers' surprise, the United States was not able to manufacture the best type of battleship armor, known as "face-hardened" (Class A in American terminology) in adequate quantities. That which it could produce was seriously inferior to, for example British and Italian armor. I am going to try to avoid a string of statistics in a Daily Content article (for those go to innumerable Internet sites) but will consider one very common comparison between Iowa and Vanguard (King George V has a virtually identical armor system, but is a smaller ship).
Put exceedingly simply, the American belt is just over 12 inches, the British just under 15 inches. However, if we take into account the relative quality of the steel, the British belt "increases" to over 17 inches. Incidentally, Italian and probably French face-hardened steel was also superior, while the Japanese is marginally inferior. Also the sad shortage of American face-hardened steel meant that only the upper half of the belt could use this type of armor.
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