20. The development of the law of international trade has gone through three stages. In the first phase it appeared in the form of the medieval lex mercatoria, a body of universally accepted rules. In the second stage it was incorporated into the municipal law of the various national States which succeeded the feudal stratification of mediaeval society. The culmination of this development was the adoption in France of the Code de commerce of 1807, in Germany the promulgation of the Allgemeine Handelsgesetzbuch of 1861, and in England the incorporation of the custom of merchants into the common law by Lord Mansfield. The third stage in the development of the law of international trade is contemporary. Commercial custom has again developed widely accepted legal concepts, particularly such trade terms as f.o.b. and c.i.f., and the institution of the bankers’ commercial credit, and international conventions have brought a measure of unification in important branches of the law of negotiable instruments, of transport by sea, air and land, of arbitration and other topics.