 The armored belt ranged in thickness from 9 to 11 in ( 229 to 279 mm ) in the more important areas of the ship . Casemated guns mounted in the hull had between 8 and 10 in ( 203 and 254 mm ) of armor plate . The barbettes that housed the main gun turrets were armored with between 4 and 10 in ( 102 and 254 mm ) of armor ; the side portions more vulnerable to shell fire were thicker , while the front and rear sections of the barbette , which were less likely to be hit , received thinner armor to save weight . The gun turrets themselves were armored with 12 in ( 305 mm ) of armor . The conning tower was 11 @.@ 5 in ( 292 mm ) thick . As in the designs of all early dreadnoughts , the deck armor was very thin at 1 @.@ 5 in ( 38 mm ) in most areas and 2 in ( 51 mm ) over machinery and magazine spaces . These ships were expected to do most of their firing at ranges less than 10 @,@ 000 yd ( 9 @,@ 144 m ) . At such distances , deck strikes would be a rare event . 
