It is matter of regret that no positive data exist in regard to the position of the oarsmen among the Ancients, because it is just on this point that vessels propelled by oars were modified in the Middle Ages. It was at this period that the oars handled by one man, according to the primitive fashion, gave place to a single bank of heavy oars each of which was worked by several rowers. This transition was not coïncident with the fall of the Western Roman Empire (476). In fact, the Emperor Leo (886 to 911) advised the construction of “dromon” biremes (~La Croix~, p. 75), and even in the XIth century, a writer is seen to speak of a _chélandre_ or _sélandre_, to which he attributes a very high speed and which had two banks of oars superposed. (~La Croix~, pp. 75 and 79.) The change came about gradually, in all probability. In the XIIIth century, only vessels with one bank of oars, galleys, are mentioned. (See, for banks, ~van Yk~, p. 11; ~Torr~, _Ancient Ships_, pp. 19 et seq.) Meanwhile, the rudder arose and its appearance brought about changes in the stern of the vessel. As a general rule, little is known about the condition of the art of shipbuilding at the beginning of the Middle Ages. All the same, however, this period must have seen an important marine on the Mediterranean and, consequently, the art of shipbuilding must have been flourishing. There is no doubt that the Crusades (1096-1291) had a great influence on the old state of affairs. Venice became the centre of progress and Genoa followed closely. The importance of the navy at this time is attested by the famous navy yards at Venice and by a great number of edicts which relate to the construction of ships. Thus, there is found in the XIIIth century an edict which determines the water line for the vessel loaded and for the vessel empty. (~Jal~, p. 267, article 4.) In regard to the construction of ships with oars, it is only necessary to refer to the edicts of the Emperor Leo which were observed, even to the Xth century. This Emperor ordered that the galleys should be sufficiently strong and swift, involving thus great length and little beam, but the latter was to be, however, proportioned to the length. These edicts were simple, but categorical. Later on, people were no longer free to build as they pleased. They had to follow the rules laid down regarding the form of the ships which bore a certain relation to the capacity and to the trips to be made. The length of the boats was not extraordinary: ~Jal~ gives, for example, a length of about 44 metres for vessels propelled by oars. This figure, as one can see, differs little from that of the vessels of antiquity, and was little exceeded later on. Just as in the times of the Greeks and the Romans, the Middle Ages had their galleys, and their merchant vessels of more rounded form. Thus, for example, the city of Genoa sent to Pisa, in 1284, a fleet of eight galleys and caravels. (~Jal~, p. 250.)