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

Peter the Hermit, an old monk on a donkey, leads the largest of the popular groups from Germany on the first crusade

Benedictine monks, wishing to return to the early ideals of the order, form a community at Cîteaux which becomes the Cistercian order

After a siege of seven months, the city of Antioch falls to the knights of the first crusade

Crusaders capture the holy city of Jerusalem and massacre the Muslim and Jewish inhabitants

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

St Bernard establishes a new monastery at Clairvaux, from which he presides over the rapid expansion of the Cistercian order

The Knights Templar are founded, to protect pilgrims from the Muslims on the journey to Jerusalem

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

A new form of pious devotion is seen in Chartres, with people painfully dragging wagons of stone to enlarge the cathedral

A bishop in the crusader territories of the Middle East has news of a fabulously wealthy Christian king, Prester John

Gilbert of Hastings, an English priest, becomes bishop of the recovered see of Lisbon - the first of many such links between England and Portugal

The second crusade is led east by two kings, Louis VII of France and Conrad III of Germany

By the time Louis VII and Conrad III reach the Holy Land they have lost more than half their joint armies to Muslim attacks

Louis VII and Conrad III do grave harm to the Latin Kingdom by a feeble attack that merely alienates the previously friendly city of Damascus

In feudal France and Germany Charlemagne is by now venerated as a saint

Resentment of western merchants results in a massacre of Roman Catholics by fellow Christians in Constantinople

A year after succeeding to the throne of England, Richard I sets off east as one of the leaders of the third crusade

The third crusade suffers an early disaster when its first leader, the emperor Frederick Barbarossa, is drowned crossing the Calycadnus river

The Muslim garrison of Acre surrenders to Richard I, who orders the massacre of 2700 of its members

The Teutonic Knights are founded to run a hospital in Acre, in the Latin kingdom of Jerusalem

The new Christian doctrine of Transubstantiation prompts rumours that the Jews desecrate the consecrated Host

The heresy of the Cathars (meaning 'pure' ones) is now so well established in southern France that they have bishops of their own

The fleet of the fourth crusade departs from Venice - only to be diverted from its purposes by Venetian guile

A German order, the Knights of the Sword, begins the forcible conversion of Latvia and Estonia to Christianity