 The main armament of the Diadem @-@ class ships consisted of 16 quick @-@ firing ( QF ) QF 6 @-@ inch ( 152 mm ) guns . Four of these were on the forecastle and in the stern , all protected by gun shields . The remaining dozen guns were in armoured casemates on each broadside . The ships carried 200 rounds per gun . Protection against torpedo boats was provided by a dozen QF 12 @-@ pounder 3 in ( 76 mm ) , 12 @-@ cwt guns , for which 300 rounds per gun was provided , and 3 QF 3 @-@ pounder ( 1 @.@ 9 in ( 47 mm ) ) Hotchkiss guns . In addition , the ships carried a pair of Ordnance QF 12 @-@ pounder 8 @-@ cwt landing guns for use ashore . The ships were also armed with a pair of submerged 18 @-@ inch ( 450 mm ) torpedo tubes . 
