"Carloman II" might refer to the second Carolingian of that name, otherwise known as Carloman I.

Carloman II (c. 866 – 12 December 884), King of Western Francia, was the youngest son of King Louis the Stammerer

Louis the Stammerer

Louis the Stammerer was the King of Aquitaine and later King of West Francia. He was the eldest son of Charles the Bald and Ermentrude of Orléans. He succeeded his younger brother in Aquitaine in 866 and his father in West Francia in 877, though he was never crowned Emperor...

 and Ansgarde of Burgundy

Ansgarde of Burgundy

Ansgarde of Burgundy was a French queen of Aquitaine, but never of West Francia, the daughter of Hardouin of Burgundy. She secretly married Louis II of France before he was king; her sons became Louis III and Carloman II of France....

, and became king, jointly with his brother Louis III of France

Louis III of France

Louis III was the King of France, still then called West Francia, from 879 until his death. The second son of Louis the Stammerer and his first wife, Ansgarde, he succeeded his father to reign jointly with his younger brother Carloman II, who became sole ruler on Louis's death...

, on his father's death in 879.

Some nobles advocated electing a sole king, but eventually both brothers were elected kings. Although doubts were cast upon their legitimacy, the brothers obtained recognition and in March 880 divided their father's realm at Amiens

Amiens

Amiens is a city and commune in northern France, north of Paris and south-west of Lille. It is the capital of the Somme department in Picardy...

, Carloman receiving Burgundy

Kingdom of Burgundy

Burgundy is a historic region in Western Europe that has existed as a political entity in a number of forms with very different boundaries. Two of these entities - the first around the 6th century, the second around the 11th century - have been called the Kingdom of Burgundy; a third was very...

 and Aquitaine

Aquitaine

Aquitaine , archaic Guyenne/Guienne , is one of the 27 regions of France, in the south-western part of metropolitan France, along the Atlantic Ocean and the Pyrenees mountain range on the border with Spain. It comprises the 5 departments of Dordogne, :Lot et Garonne, :Pyrénées-Atlantiques, Landes...

.

However, Duke Boso

Boso of Provence

Boso was a Frankish nobleman from the Bosonid-family, who was related to the Carolingian dynasty, who rose to become King of Provence ....

 had renounced his allegiance to both brothers and had been elected King of Provence

King of Burgundy

The following is a list of the Kings of the two Kingdoms of Burgundy, and a number of related political entities devolving from Carolingian machinations over family relations.- Kings of the Burgundians :...

. In the summer of 880 the brothers Carloman and Louis

Louis III of France

Louis III was the King of France, still then called West Francia, from 879 until his death. The second son of Louis the Stammerer and his first wife, Ansgarde, he succeeded his father to reign jointly with his younger brother Carloman II, who became sole ruler on Louis's death...

 marched against him, took Mâcon

Mâcon

Mâcon is a small city in central France. It is prefecture of the Saône-et-Loire department, in the region of Bourgogne, and the capital of the Mâconnais district. Mâcon is home to over 35,000 residents, called Mâconnais.-Geography:...

 and the northern parts of Boso's realm. They united their forces with those of Charles the Fat

Charles the Fat

Charles the Fat was the King of Alemannia from 876, King of Italy from 879, western Emperor from 881, King of East Francia from 882, and King of West Francia from 884. In 887, he was deposed in East Francia, Lotharingia, and possibly Italy, where the records are not clear...

 and unsuccessfully besieged Vienne

Vienne, Isère

Vienne is a commune in south-eastern France, located south of Lyon, on the Rhône River. It is the second largest city after Grenoble in the Isère department, of which it is a subprefecture. The city's population was of 29,400 as of the 2001 census....

 from August to November. Only in the summer of 882, Vienne was taken after being besieged by Richard, Count of Autun.

About the same time, in August 882, Carloman became sole king owing to his brother's death, but the kingdom was in a deplorable condition partly owing to incursions from the Norman

Normans

The Normans were the people who gave their name to Normandy, a region in northern France. They were descended from Norse Viking conquerors of the territory and the native population of Frankish and Gallo-Roman stock...

 raiders, and his power was very circumscribed. There were revolts of the feudal lords even in Burgundy.

Carloman met his death while hunting on 12 December 884 and was succeeded in the rule by his cousin, the Emperor Charles the Fat

Charles the Fat

Charles the Fat was the King of Alemannia from 876, King of Italy from 879, western Emperor from 881, King of East Francia from 882, and King of West Francia from 884. In 887, he was deposed in East Francia, Lotharingia, and possibly Italy, where the records are not clear...

.