By the last year of the First World War, the surviving ships were outdated, and six of this class were converted into blockships to be scuttled in the entrances to enemy-occupied ports in Belgium. The cruisers "Intrepid", "Iphigenia" and "Thetis" were expended on 23 April 1918 in the raid on Zeebrugge; "Brilliant" and "Sirius" were unsuccessfully expended in the similar raid on Ostend. A further attempt to block Ostend took place in May, with "Sappho" and (the latter being of the ) as blockships, but "Sappho" broke down en route to Ostend and returned to port.