Arnulf was archbishop of Reims

Archbishop of Reims

The Roman Catholic Archdiocese of Reims is an archdiocese of the Latin Rite of the Roman Catholic Church in France. Erected as a diocese around 250 by St. Sixtus, the diocese was elevated to an archdiocese around 750...

 and the illegitimate son of King Lothair of France

Lothair of France

Lothair , sometimes called Lothair IV, was the Carolingian king of West Francia , son of Louis IV and Gerberga of Saxony.-Regency:...

.

Archbishop Adalberon wanted Gerbert of Aurillac to succeed him, but King Hugh Capet accepted the elected Arnulf, a Carolingian

Carolingian

The Carolingian dynasty was a Frankish noble family with origins in the Arnulfing and Pippinid clans of the 7th century AD. The name "Carolingian", Medieval Latin karolingi, an altered form of an unattested Old High German *karling, kerling The Carolingian dynasty (known variously as the...

, in March 989. In September of that year, Arnulf supported an attempt to place his uncle Charles

Charles, Duke of Lower Lorraine

Charles of Lorraine was the son of Louis IV of France and Gerberga of Saxony and younger brother of King Lothair. He was a sixth generation descendant of Charlemagne...

, duke of Lower Lorraine, on the throne. Charles briefly held Rheims and Laon

Laon

Laon is the capital city of the Aisne department in Picardy in northern France.-History:The hilly district of Laon, which rises a hundred metres above the otherwise flat Picardy plain, has always held strategic importance...

. In 990, Arnulf refused to attend a synod at Senlis

Senlis, Oise

Senlis is a French commune located in the Oise department near Paris. It has a long and rich heritage, having traversed centuries of history. This medieval town has welcomed some of the most renowned figures in French history, including Hugh Capet, Louis IX, the Marshall of France, Anne of Kiev and...

 and he and Charles were imprisoned (March 29).

In June, 991, Seguin, Archbishop of Sens presided over a Synod of Reims in the Basilica of Saint Basle, which deposed Arnulf for alleged high treason

High treason

High treason is criminal disloyalty to one's government. Participating in a war against one's native country, attempting to overthrow its government, spying on its military, its diplomats, or its secret services for a hostile and foreign power, or attempting to kill its head of state are perhaps...

 in favour of Gerbert, later Pope Sylvester II.

This deposition was much opposed, however.