The Sirius was already in a sinking condition when at length the two ships, having failed to find the entrance, grounded, and were forced therefore to sink themselves at a point about four hundred yards east of the piers, and their crews were taken off by motor launches.

[Sidenote:  Operations cannot be rehearsed.]

The difficulty of the operation is to be gauged from the fact that from Zeebrugge to Ostend the enemy batteries number not less than 120 heavy guns, which can concentrate on retiring ships, during daylight, up to a distance of about sixteen miles.  This imposes as a condition of success that the operation must be carried out at night, and not late in the night.  It must take place at high water, with the wind from the right quarter, and with a calm sea for the small craft.  The operation cannot be rehearsed beforehand, since the essence of it is secrecy, and though one might have to wait a long time to realize all the essential conditions of wind and weather, secrecy wears badly when large numbers of men are brought together in readiness for the attack.

[Sidenote:  The Vindictive makes for Ostend.]

The Sirius lies in the surf some two thousand yards east of the entrance to Ostend Harbor, which she failed so gallantly to block; and when, in the early hours of yesterday morning, the Vindictive groped her way through the smoke-screen and headed for the entrance, it was as though the old fighting-ship awoke and looked on.  A coastal motor-boat had visited her and hung a flare in her slack and rusty rigging; and that eye of unsteady fire, paling in the blaze of the star-shells or reddening through the drift of the smoke, watched the whole great enterprise, from the moment when it hung in doubt to its ultimate triumphant success.

[Sidenote:  Unforeseen conditions add to the difficulties.]

[Sidenote:  German destroyers guard the coast.]

The planning and execution of that success had been entrusted by the Vice-Admiral, Sir Roger Keyes, to Commodore Hubert Lynes, C.M.G., who directed the previous attempt to block the harbor with Sirius and Brilliant.  Upon that occasion, a combination of unforeseen, and unforeseeable, conditions had fought against him; upon this, the main problem was to secure the effect of a surprise attack upon an enemy who was clearly, from his ascertained dispositions, expecting him. Sirius and Brilliant had been baffled by the displacement of the Stroom Bank buoy, which marks the channel to the harbor entrance, but since then aerial reconnaissance had established that the Germans had removed the buoy altogether and that there were now no guiding marks of any kind.  They had also cut gaps in the piers as a precaution against a landing; and, further, when towards midnight on Thursday the ships moved from their anchorage, it was known that some nine German destroyers were out and at large upon the coast.  The solution of the problem is best indicated by the chronicle of the event.