We have already mentioned the fore and after fighting-stages, or, as they later on became, poops and forecastles, that were erected when a ship was going on the war-path. We may note, in passing, that in the earlier part of the period we are dealing with, these were so often and so generally required that "castle-building" afloat became a recognized trade, until, in the process of evolution, poops and forecastles became integral parts of the ship. We may add that, in addition to the fore and after fighting-platforms, special fighting-towers were not infrequently erected, certainly in the Mediterranean, and we may therefore assume that they were not altogether unknown in Northern waters. These towers were generally built up round the mast, and provided with loopholes and battlements, and sometimes protected by iron plates or raw hides. One account of mediæval war-galleys states that in some cases "a castle was erected of the width of the ship and some twenty feet in length; its platform being elevated sufficiently to allow of free passage under it and over the benches". King John introduced the famous Genoese cross-bowmen--who so signally failed to distinguish themselves at Crécy--into his navy. The reason most probably was that a cross-bow could be fired through a loophole by a man crouching under cover of the bulwarks or shield-row, whereas a long-bow could not be used in this way. Nevertheless the cross-bow did not succeed in ousting the long-bow in the British Navy, since, in 1456, in the course of a public disputation between the heralds of England and France as to the claim of the former country to the domination of the sea, the French herald claimed for his countrymen that they were more formidable afloat because they used the cross-bow. "Our arbalistiers", he asserted, "fire under cover or from the shelter of the fore and after castles; through little loopholes they strike their opponents without danger of being wounded themselves. Your English archers, on the other hand, cannot let fly their arrows except above-board and standing clear of cover; fear and the motion of the ship is likely to distract their aim." But there does not seem to have been much "fear" among the English archers, and as those that were in the habit of serving afloat doubtless had their "sea-legs", it must have taken a good deal to disconcert their aim, world-renowned for its deadliness.