Oaths of Strasbourg (842): The Earliest Text in Old French

The Oaths of Strasbourg are a pair of alliance oaths sworn on 14 February 842 at Strasbourg by Louis the German and Charles the Bald, two grandsons of Charlemagne, and by their armies. Recorded word for word by the historian Nithard, they were spoken not in Latin but in the everyday languages of the soldiers. As a result they are the earliest surviving text in the Romance language that became French, and one of the earliest in Old High German.

Background: brothers against Lothar

After the death of Louis the Pious in 840, his sons fought over the Carolingian Empire. The eldest, the emperor Lothar I, claimed supremacy over his brothers. Louis the German, who ruled the lands east of the Rhine, and Charles the Bald, who held much of the west, joined forces and defeated Lothar at the Battle of Fontenoy on 25 June 841.

Lothar was beaten but not finished. He tried to win over supporters of his brothers, so Louis and Charles needed to bind themselves and their followers publicly, with an oath sworn before God that their armies would witness and understand.

What happened at Strasbourg

The two kings and their armies met at Strasbourg in February 842. Each king first addressed the assembled troops in his own language, explaining Lothar’s wrongs and their intention to stand together. Then the oaths were sworn.

Louis, as the elder, swore first, in the Romance language (lingua romana) so that Charles’s mostly western soldiers could understand. Charles then swore the same oath in the Germanic language (lingua teudisca) so that Louis’s eastern soldiers could understand. Finally the soldiers of each army swore in their own language that if their king broke the oath, they would not help him against his brother.

Louis’s oath begins with the famous words “Pro Deo amur et pro christian poblo et nostro commun salvament”, meaning “For the love of God and for the Christian people and our common salvation”. He then promised to aid his brother Charles and never to make an agreement with Lothar that would harm him. Nithard adds that the armies then took part in mock cavalry battles, an early description of a tournament-like display.

The language of the oaths

By the 9th century the spoken Latin of Gaul had changed so much that ordinary people no longer understood written Latin. The Council of Tours in 813 had already told priests to preach in the “rustic Roman language” or in German. The Romance oaths show early features that set them apart from Latin, such as new word forms and endings, while still using some Latin-style spellings.

Linguists debate exactly which dialect they reflect, and some prefer to call the language “Gallo-Romance” or “proto-French” rather than Old French. The Germanic oath is usually identified as Rhenish Franconian, a dialect of Old High German. The next major text in early French, the Sequence of Saint Eulalia, dates from around 880.

The manuscript

The oaths survive only in Nithard’s Histories, a Latin account of the civil war written by a grandson of Charlemagne who served Charles the Bald. Nithard probably wrote this part of his history in 842 or 843. The single surviving copy was made in the late 10th century, probably at the abbey of Saint-Médard in Soissons, and is now in the Bibliothèque nationale de France as MS Latin 9768. Like many texts of the period, it owes its survival to the monastic copying culture fostered by the Carolingian Renaissance.

Consequences and legacy

The alliance held. Lothar was forced to negotiate, and in August 843 the three brothers divided the empire in the Treaty of Verdun. Charles’s West Francia developed into France and Louis’s East Francia into Germany, so the two languages of the oaths have often been seen as early markers of two future nations.

Historians warn against reading modern nationalism into 842: the oaths were about loyalty between kings and warriors, not national identity. Nithard’s own choice to record the oaths in the vernacular, rather than translate them into Latin, shows how important the exact spoken words were: an oath had legal and religious force only in the form in which it was sworn. Even so, they are celebrated as the “birth certificate” of the French language and appear in French school textbooks.

Timeline

• 813: The Council of Tours orders preaching in the Romance or German languages.
• 840, 20 June: Louis the Pious dies; civil war follows.
• 841, 25 June: Louis and Charles defeat Lothar at Fontenoy.
• 842, 14 February: The Oaths of Strasbourg are sworn.
• 843, August: The Treaty of Verdun divides the empire.
• Late 10th century: The surviving manuscript of Nithard’s Histories is copied.

Why it matters

The Oaths of Strasbourg are the moment when the language that became French first appears in writing. They also capture a turning point in politics, as Charlemagne’s grandsons prepared to break his empire into the kingdoms that shaped medieval Europe.