The CMBs carried one or two torpedoes, depending on whether they were "forty footers" or "fifty-five footers". Mines could be substituted for torpedoes and they also carried depth charges and Lewis guns. It was planned that they be either towed or carried into battle on the German controlled coast by the light cruisers and destroyers of Commodore Sir Reginald Tyrwhitt's Harwich Force. With their shallow draught they could skim over the mines and attack the German patrol craft around Heligoland. As 1918 wore on a more ambitious scheme matured to send the CMBs in over the shallow coastal waters to attack the German fleet at its anchorage. However, the Armistice occurred on 11 November 1918 before these plans could be put into effect.