So far these general arrangements were applicable to both places; but, as regarded Zeebrugge, it was decided to make a diversion in the shape of a subsidiary attack on the Mole, in which men were to be landed and to do as much damage as possible. Such an attack, it was thought, would help to draw the enemy's attention from the main effort, which was to be the sinking of the block-ships, and, apart from this, would have valuable results both material and moral. For this secondary operation, three other vessels were especially selected and fitted out--two Liverpool ferry-boats, the _Iris_ and _Daffodil_, obtained by Captain Grant, not without some difficulty, owing to the natural reluctance of the Liverpool authorities {228} and the impossibility of divulging the object for which they were wanted--and the old cruiser _Vindictive_. This latter vessel had been designed as a "ram" ship more than twenty years before, displacing about 5,000 tons and capable of a speed of some twenty knots. She had no armour-belt, but her bow was covered with plates two inches thick and extending fourteen feet aft, while her deck was also protected by hardened plates, covered with nickel steel, from a half to two inches thick. Originally undergunned, she had subsequently been provided with ten 6-inch guns and eight 12-pounders. This was the vessel chosen to convey the bulk of the landing-party, and, for many weeks, under the supervision of Commander E. O. B. S. Osborne, the carpenters and engineers were hard at work upon her. An additional high deck, carrying thirteen brows or gangways, was fitted upon her port side; pom-poms and machine-guns were placed in her fighting-top; and she was provided with three howitzers and some Stokes mortars. A special flame-throwing cabin, fitted with speaking tubes, was built beside the bridge, and another on the port quarter. It was thus to be the task of the _Vindictive_ and her consorts to lay themselves alongside the Mole, land storming and demolition-parties, and protect these by a barrage as they advanced down the Mole; and, in order to make this attack more effective, yet a third operation was designed. This was to cut off the Mole from the mainland, thus isolating its defenders and preventing the arrival of reinforcements; and, in order to do so, it was decided to blow up the viaduct {229} by means of an old submarine charged with high explosives. Meanwhile, the whole attempt was to be supported from out at sea by a continuous bombardment from a squadron of monitors; seaplanes and aeroplanes, weather permitting, were to render further assistance; and flotillas of destroyers were to shepherd the whole force and to hold the flanks against possible attack.