Edward III. caused a gold noble to be struck in 1344 bearing the representation of a ship almost precisely similar to the vessel on the seal of Poole, of about twenty years earlier (Fig. 30). It is fitted with a rudder at the stern, and we may therefore conclude that at this period the side-rudder, or clavus, had disappeared from all important vessels. The fore and stern castles were, in most cases, temporary additions to merchant ships, to adapt them for purposes of warfare. In fact, nearly all the sailing-ships used in naval warfare down to, and even after the fourteenth century, appear to have been employed as merchant vessels in time of peace; and this remark applies even to the king's ships. It was, no doubt, the introduction of artillery that first caused the sailing warship to be differentiated from the merchantman. Although gunpowder for military purposes is said to have been used on land as early as 1326, and although iron and brass cannon are mentioned amongst the stores of three of the king's ships in 1338, nevertheless, the battle of Sluys and the subsequent naval engagements in the reign of Edward III. appear to have been fought without artillery. It was not till the last quarter of the fourteenth century that guns became at all common on board ship. In the year 1345 Edward III. invaded France, and was accompanied by a fleet of from 1,000 to 1,100 ships, besides small craft. Two hundred of these vessels were employed after the king's landing in ravaging the northern coasts of France and destroying the hostile shipping. In the year 1347 Edward organised another great naval expedition against France, this time in order to give him the command of the sea during his siege of Calais. The fleet was drawn from all the ports of the kingdom, and small contingents came from Ireland, Flanders, Spain, and the king's own possession of Bayonne. There are two lists in existence of the numbers of ships and men contributed by each port to this expedition. They agree very closely. According to one of them, the united fleet consisted of 745 ships, and 15,895 mariners, or an average of about twenty mariners to each ship. This figure, of course, does not include the fighting men. About fifty of these vessels were fighting ships fitted with castles, and the remainder were barges, ballingers (which appear to have been a kind of large barge), and transports. The largest contingents, by far, came from Yarmouth, which contributed 43 ships and 1,950 men; Fowey sent 47 ships and 770 men; and Dartmouth supplied 32 ships and 756 men; while London, independently of the king's own vessels, sent only 25 ships manned with 662 men.