St Peter, believed to have come to Rome as leader of the Christian community, is subsequently considered the first pope

Dionysius Exiguus, commissioned by the pope to improve chronology, makes an error of at least four years in his selected event for AD 1

Pope Gregory I negotiates with the Lombards who are threatening Rome

With papal support Pepin III is elected king of the Franks, beginning the Carolingian dynasty (named from his father, Charles Martel)

Pope Stephen II anoints Pepin III and his two sons (one of them Charlemagne) in the abbey church of St Denis

Pepin III, after recovering Byzantine territories in Italy from the Lombards, hands control of the region to the pope in Rome

In St Peter's in Rome, on Christmas Day, pope Leo III crowns Charlemagne emperor - supposedly to Charlemagne's surprise

Pope Leo III consecrates Charlemagne's new palace chapel in Aachen, modelled on San Vitale in Ravenna

The imperial coronation of Otto I by Pope John XII in St Peter's puts in place the formal role of a Holy Roman emperor

Pope Sylvester II, according to tradition, sends a sacred crown for the coronation of Hungary's first king, St Stephen

A papal delegate (from Leo IX) excommunicates Cerularius, the Patriarch of Constantinople, and the delegate is excommunicated in retaliation, launching a lasting East-West Schism

Pope Gregory VII decrees that only the church may make ecclesiastical appointments, thus initiating the investiture controversy between pope and emperor

The emperor Henry IV stands as a penitent outside the pope's castle at Canossa, so as to be released from excommunication.

Pope Urban II preaches the first crusade, urging the Christians of Europe to march east to recover Jerusalem from the Muslims

The Knights of St John of Jerusalem become an established order under papal protection

Pope Innocent III and the second Lateran council outlaw the crossbow as a weapon causing unacceptable devastation

The fall of Edessa prompts the pope, Eugenius III, to call for a second crusade to defend the Latin kingdom

The murder of the pope's legate to Toulouse provokes the Albigensian crusade, which aims to wipe out the Catharist heresy

The Dominicans are formally established by Pope Honorius III as Ordo Fratrum Praedicatorum, the Order of the Friars Preachers

Frederick II is crowned Holy Roman emperor by a somewhat reluctant pope, Honorius III

The pope, eager to fill the vacant throne of Sicily, offers it to a son of Henry III of England but gets no firm response

Pope Alexander IV establishes a third order of preaching friars, the Augustinians

Henry III accepts severe curtailment of his powers in the Provisions of Oxford, but then asks the pope to absolve him from his oath

Pope Urban IV offers Sicily to a French prince, Charles of Anjou, who marches south in 1266 to fight for the kingdom

The estates-general of France gather for the first time, in Notre Dame, to consider the king's relationship with the pope