In the Middle Ages Béziers belonged to the Viscounts of Carcassonne. When the first Cathar Crusade arived in the Languedoc this was their first target.

On 22 July 1209 the Crusader army arrived at Béziers on the periphery of the area in the Languedoc where Cathars flourished.  There were believed to be around 200 Cathars in the town among a much greater population of sympathetic Catholics. The townspeople, believing their city walls impregnable, were careless, and the town was overrun while the leading Crusader churchmen and nobles were still planning their siege.

Today nothing remains of the Viscounts' Castle in Béziers, but the town still bears scars inflicted by the Crusaders. It was here that the abbott-comander gave the famous command "Kill them all - the Lord will recognise His own"

Google map showing Château de Beziers

The crusading army sacked and looted Béziers indiscriminately, while townspeople retreated to the sanctuary of the churches.  The Cistercian abbot-commander, Arnaud Amaury, was reported by a fellow Cistercian to have been asked how to tell Cathar from Catholic.   His reply demonstrated his faith: "Kill them all - the Lord will recognise His own".  The Roman Church has recently taken to disowning these words, but they are reliable. Not only were they recorded by a sympathetic fellow churchman, but they also accord with other sources.  The Song of the Cathar Wars , sympathetic to the crusaders at this stage [laisse 21] records that the French crusaders explicitly planned to adopt a popular terrorist tactic of indiscriminate massacre (one often used by the Roman Church against those they regarded as infidels):

Le barnatges de Fransa e sels de vas Paris,
E li clerc e li laic, li princeps e·ls marchis,
E li un e li autre en entre lor empris
Que a calque castel en que la ost venguis,
Que no's volguessan, tro que l'ost les prezis,
Qu'aneson a la espaza e qu'om les aucezis;

The lords from France and Paris,
clergymen and laymen, princes and marquises,
all agreed that at every castle the army besieged
any garrison that refused to surrender
should be slaughtered wholesale
once the castle had been taken by force

When the town was taken Catholic citizens sought refuge in a Church dedicated to Mary Magdelene.

Al moster general van ilh plus tost fugir.
Li prestre e li clerc s'anero revestir
E fan sonar les senhs, cum si volguessan dir
Messa de mortuorum, per cors mort sebelhir.

Hurridly they took refuge in the high church.
The priests and clerks put on vestments
And had the church bells rung as for a funeral
And started a mass for the dead

The mass for the dead was for themselves. The Church was set alight and the rest of the town put to the sword.   Some 7,000 people died in the church including women, children, priests and old men.  Elsewhere many more thousands were mutilated and killed.  Prisoners were blinded, dragged behind horses, and used for target practice The town was razed.  Arnaud, the abbot-commander, wrote to his master the Pope: "Today your Holiness, twenty thousand citizens were put to the sword, regardless of rank, age, or sex".   Reportedly, not a single person survived, not even a new born baby.

The town of Béziers is located in the Hérault département. Today, there is almost nothing to see remaining from the period.  There is no mention of this attrocity in any of the churches in the town, but the city council has put up a number of discreet plaques commemorating the events that took place here. 

Perhaps the most enduring memorial is the sentiment "Kill them all - the Lord will recognise His own".  In Latin: Cædite eos. Novit enim Dominus qui sunt eius; in French Tuez-les tous, Dieu reconnaîtra les siens. The words - and their fulfilment - are remembered by almost everyone in the Languedoc. 

A small plaque opposite the entrance to the church at Béziers commemorates the Grand Mazel (Great Massacre)