The greatest opposition to the feudalism of the Middle Ages was found in the commercial classes. The interests of the commercial and military classes have always clashed in every age and in every nation. The constant warfare essential to the latter class is destructive of the business of the former. Trade between nations requires some system by which the relations between different countries can be regulated. It is therefore not surprising that the commercial cities of Italy and the cities of the Hanseatic League appear as pioneers in the movement for the betterment of the unsatisfactory state of international relations.

Among the earliest branches of international law to receive attention was that relative to commerce on the sea. During the Middle Ages a number of codes or systems of rules on this subject were developed.

"The so-called Amalfitan Tables seem to have been the sea law of the latter part of the eleventh century. The much more detailed Consolato del Mare, of doubtful origin, between the twelfth and fourteenth centuries derived some of its principles from the eleventh century code. The consolato was recognized by maritime powers as generally binding, and made possible wide commercial intercourse. Many of its principles have stood to the present day, though touching such questions as the mutual rights of neutrals and belligerents on the sea in time of war. As the consolato formed the code of Southern Europe, the laws of Oleron formed the maritime code for Western Europe, and were compiled the latter part of the twelfth century, whether by Richard I, or by his mother, Queen Eleanor, is a disputed question.

These laws are based in large measure on the other existing systems. The Laws of Wisby, dating from about 1288, supplemented the laws of Oleron, and formed the fundamental law of maritime courts of the Baltic nations. The Hanseatic League, in 1590, compiled a system of marine law, Jus Hanseaticum Mari-timum, based on the codes of Europe and Northern Europe. The maritime law of Europe was practically unchanged for nearly a hundred years, when systematized in 1673 under Louis XIV. Similar to the maritime codes are the 'Customs of Amsterdam,' the 'Law of Antwerp,' and the 'Guidon de la Mar.' " 1

The crusades, by the increased intercourse between nations which it occasioned, did much to increase international commerce, and thus to increase the necessity for proper regulations of this species of commerce.