 The armour protection given to the Lions was heavier than that of the Indefatigables ; their waterline belt of Krupp Cemented Armour measured 9 inches ( 229 mm ) thick amidships in contrast to the 6 @-@ inch ( 152 mm ) belt of their predecessors . It thinned to four inches towards the ships ' ends , but did not reach either the bow or the stern . In addition they were given an upper armour belt with a maximum thickness of six inches over the same length as the thickest part of the waterline armour and thinned to 5 inches ( 127 mm ) abreast the end turrets . Four @-@ inch transverse bulkheads closed off the ends of the armoured citadel . Nickel @-@ steel plating was used for the protective decks . The lower armoured deck was generally only 1 inch ( 25 @.@ 4 mm ) thick except outside the citadel where it was 2 @.@ 5 inches ( 64 mm ) . The upper armoured deck was situated at the top of the upper armour belt and was also only one inch thick . The forecastle deck ranged from 1 @.@ 25 to 1 @.@ 5 inches ( 32 to 38 mm ) . 
