The crusaders of the fourth crusade besiege, take and destroy the Christian city of Constantinople

Many of the treasures adorning the church of San Marco in Venice are loot taken from Constantinople during the fourth crusade

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

St Francis and eleven companions tell Innocent III of their wish for a life of holy poverty in the bustle of the towns

Participants in the Children's Crusade suffer disaster after the waters of the Mediterranean fail to part for them

St Dominic and his companions tell Innocent III of their wish to teach and preach in the bustle of the towns

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

St Francis of Assisi joins a crusading army in Egypt and attempts to convert the sultan Melek-el-Kamel and his followers to Christianity

The Franciscans are formally established by Honorius III as Ordo Fratrum Minorum, the Order of the Friars Minor

Frederick II, leader of the sixth crusade, briefly recovers Jerusalem for the Christians by negotiating with the Muslims

Gregory IX sends Dominican friars to root out the remains of the Catharist heresy in France, thus launching the Inquisition

The siege of the Catharist stronghold of Montségur ends when 200 heretics are herded into a wooden stockade and are burnt

Construction begins of two basilicas, one above the other on a hillside in Assisi, in memory of St Francis

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

The Jews in England are driven out of the country, soon to be followed by those in France

Boniface VIII declares a Jubilee or Holy Year, with plenary indulgences for pilgrims who make their way to Rome

Clement V moves the papacy to Avignon, in a move which is expected to be temporary but which lasts for nearly seventy years

Fifty-four Knights Templars are burned at the stake, during the campaign of the French king to destroy the order

Islam replaces Christianity as the religion of the kings of Dongola, in present-day Sudan

Moscow acquires new prestige when the metropolitan (or patriarch) of the Russian Orthodox church moves his residence from Vladimir

John Wycliffe, writing mainly in Oxford, is critical of the contemporary church and can find no basis for the pope's authority

The papal curia returns to Rome in what would seem a conclusive move if there were not, two years later, two popes - one of them elected back in Avignon

The French cardinals, objecting to the new Italian pope, elect their own man as Clement VII - and thus inaugurate the Great Schism of the papacy

Jogaila, baptized a Roman Catholic before marrying Jadwiga, brings Lithuania into the Christian fold - the last part of Europe to be converted

The followers of Wycliffe, after his death, become known as Lollards or 'mutterers'