For the fighting itself there was little need to be over-anxious; the real problem was concerned with the difficulty of approaching, throwing the men ashore, and getting them away again without the transports being sunk by the enemy’s fire. Nothing could be left to luck or the inspiration of the moment, and the conditions of success were extremely severe. First, the attacking ships must effect a complete surprise, and reach the Mole before the guns of the defence could be brought to bear upon them. The enemy searchlights must therefore be blinded, as far as possible, by an artificial fog or smoke-screen; but again this must not be dense enough to obscure the approach entirely. Secondly, the work must be done in very short time, and to the minute, for though the attack might be a surprise, the return voyage must be made under fire. The shore batteries were known to have a destructive range of 16 miles; to get clear of the danger zone would take the flotilla two hours. Daylight would begin by 3.30 a.m.; it was therefore necessary to leave the Mole by 1.30; and as, for similar reasons, it was impossible to arrive before midnight, an hour and a half was all that the time-table could allow for fighting, blocking, and re-embarking. To do things as exactly as this, a night must be chosen when wind, weather, and tide would all be favourable. The difficulty of finding so precise an opportunity caused four months’ delay—the expedition had in fact twice started and been compelled to put back: once it had actually come within 15 miles of the Mole. The attack was conducted by Vice-Admiral Roger Keyes, commanding at Dover; the force employed was a large and composite one, and required masterly handling. The Ostend expedition, though highly difficult and dangerous, was an affair of blocking only, and was comparatively simple; but for Zeebrugge there were needed, besides the principal ships, a fleet of smoke-boats for making fog, motor launches for showing flares and bringing off men in difficulties, monitors for engaging the batteries, and destroyers for looking after the enemy ships in harbour; lastly, there was an old submarine, C3, to be used as a self-propelling mine for the destruction of the viaduct. The landing on the Mole was to be made from the _Vindictive_ (Captain A. Carpenter), an old light cruiser of 5,720 tons, and she was to be accompanied by two old ferry-boats from the Mersey, the _Daffodil_ and the _Iris_; the three destroyers were the _North Star_ (Lieutenant-Commander K. C. Helyar), the _Phoebe_ (Lieutenant-Commander H. E. Gore-Langton), and the _Warwick_, flying the Admiral’s flag.