He revolted in 861 and again two years later (863); an example that was followed by the second son, Louis the Younger, who in a further rising was joined by his brother Charles the Fat. In 865, Louis was obliged by the dissidence of his sons to provide for the eventual division of his territories: Carloman was promised the kingdom of Bavaria (which Louis himself had once held under his father), together with the Ostmark; Louis the Younger was promised Saxony, together with Franconia and Thuringia; Charles the Fat was promised Swabia, together with Rhaetia.
A report that Emperor Louis II was dead led to peace between father and sons and attempts by Louis the German to gain the imperial crown for Carloman. These efforts were thwarted by Louis II, who was not in fact dead. In 876, Louis the German died and his sons inherited their lands; Carloman thus became King of Bavaria. The brothers maintained concord amongst themselves, contrary the example set by their own father and uncles and their cousins.
Upon the death of Charles the Bald of West Francia in 877, Carloman also became king of Italy and aimed at gaining the Imperial crown, but in 879, he was crippled by a stroke and divided his dominions as his father had done. He granted Louis Bavaria and Charles Italy. He had no legitimate issue, but had a concubine named Litwinde. His illegitimate son by her, Arnulf, was granted the duchy of Carinthia. Arnulf later became king of Germany and Italy and emperor.