(iv) Attack by submarines, minelayers, ship-borne M.T.B's, midget submarines and human torpedoes. The highest practicable scale of defence compatible with the importance of the base should, therefore, be planned. (b) West of 60° East and North of 10° North. Scale of attack will be little more than tip and run raids by:(i) Cruisers with 12" guns or lesser guns and smaller vessels. (ii) About 30 T.S.R. aircraft from an aircraft carrier. (iii) Small landing forces for smash and burn raids. (iv) Attack by submarines, minelayers, ship-borne M.T.B's, midget submarines and human torpedoes.