Struggle against his brothers
Kingdoms of Charles the Bald (orange) and other Carolingians in 876
He was born on 13 June 823 in Frankfurt, when his elder brothers were already adults and had been assigned their own regna, or subkingdoms, by their father. The attempts made by Louis the Pious to assign Charles a subkingdom, first Alemannia and then the country between the Meuse and the Pyrenees (in 832, after the rising of Pepin I of Aquitaine) were unsuccessful. The numerous reconciliations with the rebellious Lothair and Pepin, as well as their brother Louis the German, King of Bavaria, made Charles's share in Aquitaine and Italy only temporary, but his father did not give up and made Charles the heir of the entire land which was once Gaul. At a diet in Aachen in 837, Louis the Pious bade the nobles do homage to Charles as his heir. Pepin of Aquitaine died in 838, whereupon Charles at last received that kingdom, which angered Pepin's heirs and the Aquitainian nobles.
The death of the emperor in 840 led to the outbreak of war between his sons. Charles allied himself with his brother Louis the German to resist the pretensions of the new Emperor Lothair I, and the two allies defeated Lothair at the Battle of Fontenoy-en-Puisaye on 25 June 841. In the following year, the two brothers confirmed their alliance by the celebrated Oaths of Strasbourg. The war was brought to an end by the Treaty of Verdun in August 843. The settlement gave Charles the Bald the kingdom of the West Franks, which he had been up until then governing and which practically corresponded with what is now France, as far as the Meuse, the Saône, and the Rhône, with the addition of the Spanish March as far as the Ebro. Louis received the eastern part of the Carolingian Empire, known then as East Francia and later as Germany. Lothair retained the imperial title and the Kingdom of Italy. He also received the central regions from Flanders through the Rhineland and Burgundy as king of Middle Francia.