Battle of Fontenoy (841): Charlemagne's Heirs at War

The Battle of Fontenoy was fought on 25 June 841 near Fontenoy-en-Puisaye, south-west of Auxerre in Burgundy, between rival heirs of Charlemagne. The emperor Lothar I and his nephew Pepin II of Aquitaine were defeated by Lothar’s younger brothers Louis the German and Charles the Bald. Remembered as one of the bloodiest clashes of the early Middle Ages, it opened the way to the division of the Carolingian Empire two years later.

Background: a quarrel over Charlemagne’s empire

After the coronation of Charlemagne as emperor in 800, his empire stretched from the Pyrenees to the Elbe and into Italy. His son Louis the Pious inherited it whole in 814, but in 817 he planned a succession in which his eldest son Lothar would become emperor and senior ruler over his brothers.

The birth of a fourth son, Charles (later called “the Bald”), in 823 upset this plan, because Louis tried to carve out a kingdom for him. Repeated revolts by the older sons followed in the 830s. When Louis the Pious died on 20 June 840, Lothar claimed authority over the whole empire, while Louis the German held the lands east of the Rhine and Charles held much of the west. Pepin II, son of the late king Pepin I of Aquitaine, claimed Aquitaine and sided with Lothar.

The battle

After months of manoeuvring and failed negotiations, the armies met near Fontenoy in the early morning of 25 June 841. Most of what is known comes from Nithard, a grandson of Charlemagne through his daughter Bertha, who fought for Charles and wrote a history of the war at Charles’s request.

According to Nithard, the battle was fought in several separate engagements across the area. Louis the German broke Lothar’s forces at one point, Charles’s troops drove back their opponents at another, and a contingent under Count Adalhard fought at a third. By around midday Lothar’s army had given way and fled. The victors did not pursue far and, being Christians fighting Christians, held a three-day fast and buried the dead.

Key people

• Lothar I (795–855): Eldest son of Louis the Pious and emperor, who claimed authority over his brothers and lost the battle.
• Louis the German (c. 806–876): King of the eastern lands, whose troops broke Lothar’s line in the decisive part of the fighting.
• Charles the Bald (823–877): Youngest son of Louis the Pious and ruler of the west, later king of West Francia and emperor.
• Pepin II of Aquitaine (c. 823–after 864): Grandson of Louis the Pious, who arrived to support Lothar shortly before the battle.
• Nithard (c. 795–844): Charlemagne’s grandson, who fought for Charles and wrote the main eyewitness account.

The cost

The poet Angelbert, who fought on Lothar’s side, wrote a Latin lament for the battle, mourning the dead left unburied and calling the day cursed. Later chroniclers such as Regino of Prüm, writing around 900, claimed the Franks lost so many warriors that they could no longer defend their borders.

Nithard himself, writing soon afterwards, struggled to explain how a judgement of God had produced such suffering among Christians. The bishops of the victorious side declared that the brothers had fought only for justice and that those who had fought with a clear conscience were free of guilt, while those who had acted from hatred or ambition should do penance.

Historians treat these claims with caution. No reliable casualty figures exist, and many of Lothar’s supporters survived to fight on. Still, Fontenoy shocked contemporaries because members of the same family and the same Frankish nobility fought each other in a pitched battle, something Carolingian rulers had usually tried to avoid.

Consequences

Fontenoy did not end the war, but it destroyed Lothar’s hope of ruling the whole empire. Louis and Charles sealed their alliance publicly in the Oaths of Strasbourg in February 842, and after further campaigning Lothar agreed to talks. In August 843 the three brothers divided the empire in the Treaty of Verdun, which created the kingdoms from which France and Germany eventually emerged.

Pepin II was left out of the settlement, and Aquitaine remained contested for years. Meanwhile, Viking raiders took advantage of the civil war, attacking Rouen in 841 and Nantes in 843.

Timeline

• 817: Louis the Pious plans for Lothar to succeed him as senior emperor.
• 823, 13 June: Charles the Bald is born.
• 840, 20 June: Louis the Pious dies; civil war between his sons begins.
• 841, 25 June: Battle of Fontenoy; Lothar and Pepin II are defeated.
• 842, 14 February: Louis and Charles swear the Oaths of Strasbourg.
• 843, August: The Treaty of Verdun divides the empire.
• 1860: An obelisk is erected at Fontenoy to commemorate the battle.

Why it matters

Fontenoy marked the end of the dream of a single Frankish empire under one ruler. It turned a family quarrel into a lasting division of western Europe and is often seen as a starting point for the separate histories of France and Germany.