Treaty of Verdun

The Treaty of Verdun (843) happened two generations after Charlemagne and divided his empire into three parts. When Charlemagne's son Louis the Pious died in 840, his oldest son Lothair I said that he ruled his younger brothers and their lands. But his brothers Louis the German and Charles the Bald won the Battle of Fontenoy (841).
Division of the empire.
Each of the brothers already had one kingdom - Lothair in Italy, Louis the German in Bavaria, and Charles the Bald in Aquitaine.