The Siege of Termes (1210), according to the "Historia Albigensis"
The major text witch allows us to know the siege of Termes is this extract of the "Historia Albigensis" by Peter (Pierre) of les Vaux de Cernay. He is one of the most important sources for the Albigensian Crusades. It is likely that he traveled with the Crusader armies of Simon de Montfort, it's "hero". Therefore, the chronicle ends when Simon dies in 1218... Peter of les Vaux de Cernay was an eyewitness to many of the events he describes. If it's not, he did talk with the witnesses. That's why the facts, places and details which he describes comes true nowadays on the site.
He supports the crusaders wholeheartedly, and often portrays their enemies in a very negative light : see how he talks about Raimond of Termes here. Thus, the chronicle is very partial, as you will see. The following portion, from sections 168 to 192 of chapter 7, of his work Historia Albigensis, deals with the siege of Termes in 1210. The lenght of this part shows the importance of this four months in the Corbieres hills...
If you did not already read that, see another version, with the account by "The Song of the Cathar Wars" of William de Tudela.
This translation is from The History of the Albigensian Crusade: Peter of les Vaux-
 The Count proposes to besiege Termes. At this time a crusader of noble rank, William of Cayeux, arrived from France, with some other crusaders. The Count was told that a large force of Bretons was on its way. After taking counsel with his followers, and trusting in God's help, the Count led his forces to besiege Termes.
 Whilst he was on his way, the knights in Carcassonne had some siege-
 The Bretons whom I mentioned above reached Castelnaudary on their way to join the Count. This place was in the territory of Toulouse and still controlled by the Count of Toulouse. The townsmen refused to allow them into the town, but compelled them to pass the night in the fields and gardens; indeed the Count of Toulouse continued surreptitiously to hinder Christ's business as much as he could. When the Bretons reached Carcassonne they followed our Count on his way to besiege Termes, taking the siege-
 The lord of this place was a knight named Raymond who as an old man had become given over to a reprobate mind; a manifest heretic who (to describe his evil nature in a few words) feared not God neither regarded man. So confident was he in the strength of his castrum that from time to time he was prepared to take up arms against the King of Aragon, the Count of Toulouse or his overlord the Viscount of Beziers. When this tyrant heard that our Count planned to besiege Termes he gathered together as many knights as he could, filled the castrum with large stores of food and whatever else he needed for its defence and prepared to withstand the siege.
 Siege of Termes. Arriving at Termes, our Count started the siege with a modest force and was able to occupy a small part of the castrum. The defenders, numerous and well protected, showed no fear of our modest army; they were able to come and go freely to obtain water and whatever else they needed whilst our men watched, too weak to oppose them. Whilst this and similar events were taking place small groups of French crusaders were arriving each day to join the army. Seeing them arrive, our adversaries climbed the walls and poured down abuse on our men, because the newcomers were so few and poorly armed, calling derisively: "Fly from the sight of the army, fly from the sight of the army!" Soon afterwards crusaders began to come in large groups from France and Germany, whereupon the enemy began to be afraid, stopped heaping insults on us and became less bold and confident. Meanwhile the Lord of Cabaret, the chief and most cruel enemies of the Christian religion at that time, patrolled the public roads near Termes night and day and whenever they carne across any of our men either condemned them to a shameful death or, to show their contempt for God and our side, most cruelly put out their eyes and cut off their noses and other members, and sent them back to the army.
 Arrival of the Bishops of Chartres and Beauvais and many other nobles. So matters stood when a number of noble and powerful men arrived from France; Renaud, Bishop of Chartres, Philip, Bishop of Beauvais, Count Robert of Dreux and also the Count of Ponthieu. They were accompanied by a substantial force of crusaders whose arrival greatly cheered the Count of Montfort and the whole army. It was hoped that strong action would result from the arrival of these powerful men; and that they would grind down the enemies of the Christian faith with a strong hand and a stretched out arm. But He who puts down the mighty and gives grace to the humble, through some secret design known only to Himself, wished nothing great or glorious to be achieved by their hand. As far as human reasoning can determine, the just judge so acted either because they were not worthy to be the instrument for the great and worshipful God to do great and wonderful things; or because if great men were to perform any great deed it would be ascribed entirely to human power, and not Divine. So, the Heavenly Disposer thought it better to keep that victory for the humble, so that by winning through them a glorious triumph He might give glory to His own great name. Meanwhile our Count had siege-
 Such was the state of affairs when our men realised that their attempts to capture the castrum were being severely impeded by the tower of Termenet which I described above, and which was defended by a body of knights, and they began to consider how they might capture it. They therefore set guards at the base of the tower (which, as I mentioned, was built on the summit of a high crag), so as to prevent the men in the tower having access to Termes itself or those in the castrum providing help to the tower if need arose. After a few days our men succeeded, with great difficulty and at great risk, in erecting a siege-
 Whilst this was going on, our petraries on another side of the castrum kept up a continuous bombardment of the walls. When our adversaries -
 Meanwhile our men erected a mangonel in an inaccessible place at the foot of a crag near the wall, which inflicted no slight damage on our enemies when it was put to use. Our Count sent a force of three hundred sergeants and five knights to defend the mangonel; there was great concern for its safety, because our men knew that our opponents would spare no effort to destroy an engine that was causing them so much trouble, and also because the difficulty of access to the mangonel would make it impossible for the main army to help those guarding it in a emergency.
One day a force of enemy soldiers, up to eighty in number, protected by shields, rushed out to destroy the mangonel, followed by a huge number of other men carrying wood, fire and other materials for setting light to the mangonel. When they saw the enemy coming the three hundred sergeants guarding the mangonel were seized with panic and fled, leaving only the five knights to maintain the defence. What more? When the enemy drew near all the knights fled save one, William of Ecureuil. This knight, seeing the enemy approaching, began with great difficulty to climb over the crag to meet them; they made a concerted rush against him, and he defended himself vigorously. They saw that they could not capture him, and instead thrust him with their spears onto the mangonel, and threw dry wood and fire after him. This courageous man at once rose up and dispersed the fire, so that the mangonel was unharmed. Once again he started to climb up to face the enemy; once again they thrust him back and threw fire on him. Again he rose up and went for the enemy; four times in all they hurled him onto the mangonel. Finally our men realised that since no one from our side could reach our knight to help him, he would be unable to escape; they therefore went to another part of the wall and made as if to mount an attack, whereupon the enemy soldiers harassing William retired into the castrum. William, albeit exhausted, escaped alive. His incomparable courage had ensured that the mangonel was unharmed.
 At this time the noble Count of Montfort was beset by extreme poverty, to the extent that he was very often even short of bread, and had nothing to eat. Frequently -
 So matters stood when our opponents ran out of water, for our soldiers had cut off the approaches to the castrum and they could not get out to draw water. Lack of water produced lack of courage and of the will to resist. What more? They started to parley with us, and sought to negotiate peace on these terms: Raymond, the lord of Termes, promised to hand it over to the Count provided the Count allowed him to retain all his other possessions; also the Count was to return Termes to him after Easter.
Whilst discussions on these proposals were going on, the Bishops of Chartres and Beauvais, Count Robert of Dreux and the Count of Ponthieu proposed to leave the army. The Count begged them to stay a little longer to carry on the siege, and everyone else added their pleas; but as they could not be diverted from their purpose, the noble Countess of Montfort threw herself at their feet and begged them passionately not to turn their backs on the Lord's business in the hour of such great need, and to give help at this time of crisis to the Count of Jesus Christ, who every day was exposing himself to mortal danger on behalf of the Catholic Church. The Bishop of Beauvais, Count Robert and the Count of Ponthieu were unmoved by the Countess's prayers, but said that they would leave the next morning and were quite against staying even for one more day. The Bishop of Chartres, however, promised to remain with the Count for a short time longer.
 The following night, there was a sudden intense rainstorm, as if the sky had broken apart and the floodgates of heaven had opened. So great was the downpour that our enemies, who had long suffered from an extreme shortage of water, and had for this reason proposed to surrender to us, now found themselves with an abundant supply. Our harp is turned to mourning, the grief of our enemies is changed to joy! They at once became arrogant and recovered their courage and the will to resist. Their cruelty, their eagerness to oppose us, increased, the more so because they dared to think the storm was a sign that some Divine aid had come to them in their hour of need. What a vain and unjust presumption, to boast of help from Him whose worship they despised, whose faith they had rejected! They said indeed that God did not wish them to surrender; all this, they asserted, had been done for their benefit -
 At first light the Count sent to Raymond, the lord of the castrum, ordering him to hand it over as he had promised on the previous day. Raymond, however, who now had water in plenty instead of the shortage which had produced his willingness to surrender and who also saw that almost the whole strength of the army was leaving, changed his mind and wormed his way out of his undertaking. However, two knights in Termes who had on the previous day given firm promises of surrender to the Count's Marshall did come out and give themselves up to the Count.
When the Marshal, who had been instructed by the Count to go in person to parley with Raymond, returned and reported what the latter had said, the Bishop of Chartres (who wanted to leave next day) urged that the Marshal should be sent again to Raymond and offer a truce on whatever terms were acceptable to him, so long as he agreed to hand over the castrum. In the hope that it would help in persuading Raymond to agree, the Bishop further advised that the Marshal should take with him the Bishop of Carcassonne, who was with the army, because he was a native of the area and was known to the murderous lord of Termes; moreover the bishop's mother -
 The Count saw that with the departure of these nobles, that is the Bishops and the Counts, he was virtually alone and almost deserted. He was now extremely anxious and concerned, and did not know what to do. He did not want to abandon the siege, but could not stay where he was any longer; he had many well-
 Whilst the Count was thus troubled and distressed and at a loss what to do, one day a contingent of crusaders on foot came on the scene from Lorraine. The Count was delighted by their arrival and strengthened the siege. With the industrious help of Archdeacon William, our men regained their spirits and began to work hard on everything concerned with the siege. At once the siege-
 After our men had spent some time working on the machines and had succeeded in weakening a large section of the keep, one day, the feast of St Cecilia, the Count had a trench carefully dug out and covered with hurdles, which would allow sappers to approach the wall and dig under it. The Count spent the whole day on the preparation of the trench without breaking off to eat, and as night approached -
 After the capture of Termes, on the eve of the feast of St Clement, and its occupation by our troops, the Count led his forces to a castrum named Coustaussa. Finding it deserted he went on to another castrum named Puivert, which surrendered within three days.