The pledges exchanged on this occasion are as interesting to the student of language as to the historian. The army which accompanied Louis was composed of men of almost pure Germanic blood and speech, while that with Charles was made up of men from what is now southern and western France, where the people represented a mixture of Frankish and old Roman and Gallic stocks. As a consequence Louis took the oath in the _lingua romana_ for the benefit of Charles's soldiers, and Charles reciprocated by taking it in the _lingua teudisca_, in order that the Germans might understand it. Then the followers of the two kings took oath, each in his own language, that if their own king should violate his agreement they would not support him in acts of hostility against the other brother, provided the latter had been true to his word. The _lingua romana_ employed marks a stage in the development of the so-called Romance languages of to-day--French, Spanish, and Italian--just as the _lingua teudisca_ approaches the character of modern Teutonic languages--German, Dutch, and English. The oaths and the accompanying address of the kings are the earliest examples we have of the languages used by the common people of the early Middle Ages. Latin was of course the language of literature, records, and correspondence, matters with which ordinary people had little or nothing to do. The necessity under which the two kings found themselves of using two quite different modes of speech in order to be understood by all the soldiers is evidence that already by the middle of the ninth century the Romance and Germanic languages were becoming essentially distinct. It was prophetic, too, of the fast approaching cleavage of the northern and southern peoples politically.