The occasion of these oaths was the alliance between the two brothers, Ludwig the German and Charles the Bald, against their brother Lothar. Lothar had been defeated at the battle of Fontenay, 841, by his brothers, who then made this league. The oaths are given in this form by Nithard, the historian of the later Carolingians, who was the son of Angilbert and Bertha, the daughter of Karl the Great. The _lingua romana_ and the _lingua teudisca_ are the vulgar languages respectively of the followers of Charles the Bald and Ludwig the German, that is, of the inhabitants of France and of Germany. The appearance of a Latin dialect as the language of the inhabitants of the western kingdom indicates that the Roman elements had after all survived in Gaul and were absorbing the German elements; the formation of two languages mutually exclusive in the two portions of the empire suggests a fairly advanced stage of differentiation between the German and the French parts. But the chief interest of this document is in the field of language study. The _lingua romana_ shows an early stage in the development of French from Latin, while the _lingua teudisca_ is one of the earliest forms of Old High German. The _lingua romana_ shows the process by which the French language grew out of Latin; note that inflectional endings have largely disappeared, and case is shown by the use of prepositions, and that phonetic changes (changes of vowels and consonants) have also taken place. Some of the words are good Latin, others are very nearly modern French, and still others stand midway between Latin and French. Most of the words in the _lingua teudisca_ can be identified with modern German words. Note that each leader took the oath in the language of the followers of the other, in order that his brother's followers might understand him. So Ludwig the German speaks in the _lingua romana_ and Charles the Bald in the _lingua teudisca_. So Ludwig and Charles came together at Argentaria, which is called Strassburg in the common tongue, and there took the oaths which are given below, Ludwig speaking in the _lingua romana_ and Charles in the _lingua teudisca_.... Ludwig, being the elder, took the oath first, as follows: Pro deo amur et pro christian poblo et nostro commun salvament, d'ist di in avant, in quant deus savir et podir me dunat, si salvaraeio cist meon fradre Karlo et in aiudha et in cadhuna cosa, si cum om per dreit son fradra salvar dist, in o quid il mi altresi fazet, et ab Ludher nul plaid numquam prindrai, qui meon vol cist meon fradre Karle in damno sit. When Ludwig had finished, Charles took the oath in the _lingua teudisca_: