The purposes of the expedition, as we have seen, were to block the exit of the canal at Zeebrügge and the entrance of the small, narrow harbour at Ostend with old cruisers filled with cement, the removal of which would be an operation of a lengthy and tedious kind. Incidentally, the plan was to effect the maximum destruction of war stores and equipment at Zeebrügge and to sink as many as possible of the enemy vessels found in either port, and finally, to inflict on the enemy the maximum possible losses of personnel. By blocking the canal the value of Zeebrügge was reduced from being an equipped base to being a mere refuge. As there were two points of attack, the expedition naturally resolved itself into two distinct, but simultaneous, undertakings. The simpler, the less dangerous, the less ambitious, but, as the event showed, the more difficult operation of the two, was the attempt to block Ostend. The larger, more complex, and infinitely more perilous undertaking, but because of its very complications, ultimately easier, was the attempt at Zeebrügge. In its broad outlines, the scheme was to get the ships as near as possible without detection, and then to trust to a final rush to gain the desired position. Concealment up to the last moment was to be secured by smoke screens. At Ostend the problem was simply to run two or three ships into the entrance--that is, to get them into position before the enemy’s artillery made it impossible to manœuvre. If the Ostend attempt failed, it was largely because a sudden change in the weather conditions robbed the smoke screens, which were to hide the ships, of their value, so that the operation of placing the block-ships accurately was made almost impossible. The operation of blocking such entrances has, of course, long been familiar. The exploit of Lieutenant Hobson in the Spanish-American War, is fresh in the memories of all sailors. This failed through the steering gear of the blocking-ship being destroyed by gunfire at the critical moment. The Japanese attempted the same thing on a large scale at Port Arthur but with anything but complete success. If the first Ostend effort, then, fell short of finality, we have the experience of these earlier precedents to explain and account for it.