346 THE HISTORY OF MEDIEVAL EUROPE that all merchantmen should be marked with a load-line. A vessel one hundred feet long was then regarded as of great size, although some war galleys were longer than that. Two hundred and fifty tons was considered a good cargo. Where oars were used, a crew of nearly two hundred men was often needed, several of them working at one oar. The vessels used in transporting crusaders to the East some- times were loaded with as many as a thousand men each, if we credit the sources. By the fourteenth century the rud- der had replaced the old method of steering by one or two oars at the stern. While Venice was becoming a great sea power, the towns on the mainland had also developed apace. Under the early The Lom- ru ^ e °^ their counts or bishops the townsmen, bard com- with the possible exception of a few prominent families, had little or no share in the govern- ment and might even be without personal freedom. But the opening of the twelfth century reveals a great change in northern Italy. In the Lombard cities the townsmen have abolished the rule of the bishop and have taken the reins of government into their own hands, aided by the confu- sion attendant upon the investiture strife when there were two claimants for almost every bishopric. The townsmen effected this revolution by forming communes, in which the nobles resident in the cities combined with the other free inhabitants to secure the direction of the town government. The nobles in the Lombard cities at this time were divided into the two classes of capitani and valvassores. The Social "captains" had originally been those who held the Lom- great fiefs directly from the bishop or the em- bard cities peror, while the "valvassors" were the subvas- sals who held under the captains or great landholders. There were a number of such nobles connected with each city because most Italian cities controlled a considerable circuit of adjoining territory. But by the twelfth century nobility had ceased to depend exclusively upon birth or the possession of a large landed estate. Wealth acquired by commerce was also a road to nobility, and we are even told
