#52 The Oaths of Strasbourg: Characteristics and Historical Background

French is a language that developed over many centuries from Latin, which was spoken in the ancient Roman Empire.

One of the most important historical documents for tracing this development is the Oaths of Strasbourg (Serments de Strasbourg), which date from 842.

The Oaths of Strasbourg were political oaths of alliance exchanged in Strasbourg, a city located in what is now northeastern France. The surviving record contains passages in Old French, the ancestor of modern French, and Old High German.

Strictly speaking, the language used in the oaths represents a transitional stage between Latin and Old French. Nevertheless, the document is regarded as an important source of early Old French in the history of the French language.

In this article, I will explain the historical background of the Oaths of Strasbourg, the languages used in the oaths, their linguistic characteristics, and their significance in the history of French.

1. What Are the Oaths of Strasbourg?

The Oaths of Strasbourg (Serments de Strasbourg) were oaths of alliance exchanged on February 14, 842, between Louis the German (Louis le Germanique) and Charles the Bald (Charles le Chauve), two members of the Carolingian dynasty.

Both were sons of Emperor Louis the Pious and grandsons of Charlemagne.

At the time, the Frankish Empire was experiencing a prolonged conflict over the inheritance of territory following the death of the emperor.

Against this background, Louis the German and Charles the Bald gathered in Strasbourg, in what is now northeastern France, on February 14, 842. In the presence of their respective armies, they pledged to cooperate against their elder brother, Lothair I (Lothaire Ier).

In addition to promising mutual cooperation against Lothair I, the oaths established that the soldiers of each army would refuse to support their own ruler if he broke his oath and acted against the other ruler.

A distinctive feature of the Oaths of Strasbourg is that they were spoken in Old French and Old High German, languages understood by the soldiers, rather than in Latin, which was widely used for official records at the time.

Louis the German delivered his oath in Old French, while Charles the Bald delivered his in Old High German. In this way, each ruler communicated the terms of the alliance to the other ruler’s army.

The Oaths of Strasbourg are therefore both a record of a political alliance formed during the conflicts within the Frankish Empire and an important historical source for understanding language use during this period.

In particular, the Old French recorded in the oaths has been studied by linguists and historians as valuable evidence of the development of French from Latin.

2. Historical Background of the Oaths of Strasbourg

The Oaths of Strasbourg arose from political conflicts over the succession and division of the Frankish Empire.

During the late eighth and early ninth centuries, the Frankish Empire expanded under the rule of Charlemagne, becoming a powerful state that controlled extensive territories across Western Europe.

In 800, Charlemagne was crowned emperor by Pope Leo III, strengthening his political authority in Western Europe.

Following Charlemagne’s death in 814, his son Louis the Pious (Louis le Pieux) inherited the empire.

Louis the Pious attempted to preserve imperial unity, but disputes over the distribution of territories among his sons gradually destabilized the political situation within the empire.

When Louis the Pious died in 840, the struggle over the inheritance of imperial territories intensified.

The three principal figures involved in the conflict were:

• Lothair I (Lothaire Ier)
  — Inherited the imperial title and claimed supremacy over the entire empire.
• Louis the German (Louis le Germanique)
  — Established his principal power base in the eastern part of the empire.
• Charles the Bald (Charles le Chauve)
  — Established his principal power base in the western part of the empire.

While Lothair I asserted his authority over the entire empire, Louis the German and Charles the Bald began cooperating to protect their respective territories and political positions.

In 841, their combined forces fought against Lothair I’s army at the Battle of Fontenoy (bataille de Fontenoy) and emerged victorious.

However, the battle did not completely resolve the territorial disputes, and the two rulers needed to maintain their alliance.

Consequently, on February 14, 842, Louis the German and Charles the Bald gathered in Strasbourg and formally pledged to cooperate against Lothair I.

This event became known as the Oaths of Strasbourg.

The oaths reaffirmed their alliance and contributed to the political developments that eventually led to the division of the empire.

In 843, the Treaty of Verdun (traité de Verdun) was concluded, dividing the Frankish Empire into three major territories.

Lothair I retained the imperial title and the central territories, while Louis the German received the eastern territories and Charles the Bald received the western territories.

The resulting kingdoms of West Francia and East Francia became important foundations for the eventual development of France and Germany through a long historical process.

3. Why Were the Oaths Spoken in Two Different Languages?

One of the most distinctive characteristics of the Oaths of Strasbourg is the use of two different languages: Old French and Old High German.

At the time, the Frankish Empire controlled extensive territories stretching across Western and Central Europe, and the languages spoken by its inhabitants varied from region to region.

In many western regions of the empire, people spoke early forms of Old French and other Romance varieties that had developed from Latin. In many eastern regions, Germanic languages, including Old High German, were spoken.

Latin continued to play an important role in religion, scholarship, and administration. In everyday conversation, however, people generally used the languages that had developed in their respective regions.

For this reason, the Oaths of Strasbourg were delivered in a manner that allowed the soldiers of both armies to understand their content.

• Louis the German
  — Delivered his oath in Old French, which was understood by the soldiers from the western territories.
• Charles the Bald
  — Delivered his oath in Old High German, which was understood by the soldiers from the eastern territories.

In other words, each ruler used a language that the other ruler’s soldiers could understand.

The soldiers of both armies also swore their own oaths in their respective languages. This allowed not only the rulers but also their armies to confirm their commitment to mutual cooperation.

The Oaths of Strasbourg therefore demonstrate how people speaking different languages could cooperate in pursuit of a common political objective.

4. What Was the Old French Used in the Oaths?

The Old French used in the Oaths of Strasbourg was an early form of the language from which modern French developed.

French originated from Latin, which spread throughout Gaul under the rule of the ancient Roman Empire.

When Gaul came under Roman control during the first century BC, Latin gradually became widespread and influenced the languages spoken by the local population.

Following the decline of the Roman Empire and the migration of Germanic peoples, the Latin spoken in Gaul underwent its own distinctive changes.

Pronunciation, vocabulary, and grammar gradually evolved, and the language used in everyday life developed characteristics that differed from those of Classical Latin.

Old French emerged through this process of linguistic change.

Old French was spoken primarily in what is now northern France from approximately the ninth to the fourteenth centuries. It differed from modern French in various aspects of pronunciation, grammar, and spelling.

The language recorded in the Oaths of Strasbourg provides evidence of an early stage in the development of Old French.

For example, the opening of the oath contains the following passage:

• Original text:
  Pro Deo amur et pro christian poblo et nostro commun salvament
• Modern French paraphrase:
  Pour l’amour de Dieu, pour le peuple chrétien et pour notre salut commun.
• English translation:
  For the love of God, for the Christian people, and for our common safety.

This passage reveals several similarities with modern French.

For example, the word amur in the original text corresponds to modern French amour (love). Similarly, poblo corresponds to peuple (people), while nostro corresponds to notre (our).

These words are derived from Latin, and their pronunciation and forms changed over time.

At the same time, the original passage contains words such as Deo (God) and pro (for), which retain forms closely resembling Latin.

The Oaths of Strasbourg therefore contain both characteristics inherited from Latin and newer features associated with the subsequent development of French.

For this reason, the document is a valuable source for examining the linguistic changes that occurred during the transition from Latin to Old French.

5. Why Are the Oaths Considered One of the Earliest French Documents?

The Oaths of Strasbourg are often described as the earliest written document in French.

This is because they preserve passages written in an early form of Old French that was distinct from Latin.

In early medieval Western Europe, Latin was widely used in religion, scholarship, and administration.

In everyday life, however, people spoke regional languages that had developed over time. In the territories corresponding to present-day France, varieties derived from Latin gradually acquired characteristics associated with Old French.

Nevertheless, most written documents from this period were produced in Latin. As a result, relatively few sources directly preserve the languages used in everyday speech.

The Oaths of Strasbourg are particularly important because they contain a substantial passage recorded in early Old French during this period.

Of course, this does not mean that French suddenly emerged in 842. French developed from Latin through linguistic changes that took place over several centuries, and the Oaths of Strasbourg preserve evidence of an early stage in that process.

Other important documents providing evidence of early Old French also appeared during the ninth century.

One notable example is the Sequence of Saint Eulalia (Séquence de sainte Eulalie), which is believed to have been composed around 880.

This work is a religious poem about Saint Eulalia, a Christian martyr, and is recognized as one of the earliest surviving literary works written in early Old French.

Thus, the Oaths of Strasbourg are among the earliest surviving substantial written records of French, while the Sequence of Saint Eulalia is among the earliest surviving works of French literature.

Together, these documents provide valuable evidence of the characteristics of ninth-century French and the contexts in which it was used.

6. The Recording and Preservation of the Oaths Through Manuscripts

The contents of the Oaths of Strasbourg have survived to the present day because they were recorded by the ninth-century historian Nithard.

Nithard was a grandson of Charlemagne and served Charles the Bald. He wrote about the political conflicts and disputes among members of the royal family that took place within the Frankish Empire.

His work, Historiarum libri IV (Four Books of Histories), contains an account of the circumstances surrounding the Oaths of Strasbourg, as well as the oaths sworn by the two rulers and their soldiers.

Although the work was written primarily in Latin, Nithard preserved the texts of the oaths in Old French and Old High German.

Since Latin was widely used in historical writing and official documents at the time, the preservation of passages in the languages actually used during the event is particularly significant from the perspective of linguistic history.

The Oaths of Strasbourg were also preserved because Nithard’s work was copied by later generations.

The oldest surviving manuscript is not the original document produced in 842, but a copy made around the tenth century.

In medieval Europe, manuscripts were produced in monasteries and other institutions to preserve written works for future generations.

Before printing technology became widespread, copying books by hand was the principal means of preserving and transmitting written texts.

During this process, changes in spelling and expression could occur.

For this reason, linguists and historians study the text of the oaths while also considering the period in which the surviving manuscript was produced and the characteristics of its transcription.

Today, the manuscript of Nithard’s work containing the Oaths of Strasbourg is preserved at the Bibliothèque nationale de France (National Library of France).

7. Summary

The Oaths of Strasbourg were political oaths of alliance exchanged between Louis the German and Charles the Bald in 842.

The most important points can be summarized as follows:

The Oaths of Strasbourg arose during the conflicts over the succession of territories within the Frankish Empire and became an important event connected to the subsequent history of Western Europe.

Furthermore, because the oaths were recorded in early Old French and Old High German, they remain valuable historical sources for studying the development of the French language.

Izumi Miyajima

Writer

I’m a Japanese writer and language enthusiast with a deep interest in France. Through my articles, I explore the French language, history, and culture.