The attack on Ostende in May, 1798, was directed against the lock gates for the purpose of interfering with the concentration of the flotillas destined for the invasion of England. This attack had originally included a blocking operation, but that idea was apparently abandoned. The attack, carried out in the face of a rather feeble defence, was completely successful, but a severe gale prevented the {56} re-embarkation of the forces, with the result that over one hundred and sixty were killed or wounded and nearly eleven hundred and fifty were taken prisoners--an interesting point in view of the fact that only about half a dozen casualties occurred during the attack itself. The embodiment of the main principles of fighting led to success on that occasion as they will usually do under similar conditions. The moral effect in England, in spite of the heavy losses, is recorded as having been most beneficial. The blocking attempts at Santiago and Port Arthur, carried through with complete indifference to danger in each case, were failures. [Sidenote: Main Factors of Difficulty] The main difficulties with which blockships must contend may be briefly stated as follows: (_a_) That of _locating the destination_ in darkness, increased by the absence of the usual local navigational aids such as lighthouses, buoys, etc. (_b_) That of _reaching the destination_, when located, in the face of the enemy's opposition. (_c_) That of _turning and sinking the vessel_, after reaching the destination, so that the channel will be efficiently blocked. Dealing with these difficulties in detail, the reader is probably aware of the fact that navigation is by no means an exact science. On the open sea a captain is usually satisfied if he knows his position to within three or four miles. When approaching the coast this wide margin of safety must be considerably reduced--hence the need of lighthouses, buoys, fog signals, and so forth. The upkeep of such aids is naturally in the hands of the power which occupies the coast {57} concerned. Thus, under war conditions, one aims at removing all navigational aids, as far as one's own requirements will allow, which may assist the enemy. By this means, the enemy when approaching one's coast, must either trust to the rather inexact methods used in the open sea or they must establish their own navigational aids beforehand. The objection to the latter is manifest; craft sent ahead to lay down buoys, etc., are apt to give one's intentions away, and it is open to the enemy to remove such aids as soon as they are placed. With regard to the second main difficulty, namely, that of reaching the destination, when located, in the face of the enemy's opposition, the difficulty here is so obvious as to render detailed remarks unnecessary.