Guillaume de Sonnac Guillaume de Sonnac was Grand Master of the Knights Templar from 1247 to 1250 . Personal life . Sonnac was born to a noble family in the French region of Rouergue . No date of birth survives for the Grand Master . He was described by Matthew Paris as " a discreet and circumspect man , who was also skilled and experienced in the affairs of war " . De Sonnac was an established member of the order before his election as Grand Master . He was the Preceptor of Aquitaine in France for the Templars and arrived in the Holy Land around autumn of 1247 , finding " the remnants of the Kingdom of Jerusalem in a precarious state . Grand Master Armand de Périgord had been taken prisoner at the Battle of La Forbie in 1244 , and after negotiations for his release failed two years later , De Sonnac was proposed as a replacement . Before his first year in the East was out , he was the order ' s new leader . Military Record . The Seventh Crusade . De Sonnac ' s tenure was a particularly violent one . By 1247 , the Christians had lost power bases in Tiberias , Mount Tabor , Belvoir and Ascalon . This prompted a fresh campaign from King Louis IX of France , who landed at Limassol , Cyprus on 17 September 1248 . De Sonnac sailed from Acre to meet him and make preparations . Shortly after , the new Grand Master received an Emir from the Sultan , offering the crusaders a peace deal . De Sonnac related this to the French King , who ordered him to cease any negotiations without gaining Royal permission first . This ensured the new campaign would be concluded with violence , not diplomacy . The Siege Of Damietta . On 5 June 1249 , the French crusader army , combined with de Sonnac and his Templar knights , attempted to land in Egypt . They targeted Damietta , just as the Fifth Crusade had years earlier . Fighting on the Egyptian beaches was heavy and the King fought in waist - high water alongside the troops . After a prolonged battle , the Muslims were forced to retreat , leaving the city almost undefended . The next day the de Sonnac wrote to Robert of Sandford , telling how on the morning after the battle , Damietta had been seized with only one crusader casualty At the end of November , de Sonnac and King Louis began their march to Cairo , via Mansurah . Battle of Al Mansurah . De Sonnac ' s next engagement was at the Battle of Mansurah , for the city containing the area ' s defensive force , the last obstacle to central Egypt . The Muslims had been protected by the swollen Nile , but on 8 February 1250 , a local Bedouin showed them where they could cross . De Sonnac , Robert of Artois , the King ' s brother and William II Longespee , leader of the English troops , launched an assault on the Muslim force without the main Frankish army . Taken by surprise , the Egyptians quickly retreated from the riverbank into the city and the Count foolishly gave chase , outnumbered and with no back - up from the bulk of the French forces . John of Joinville claimed that the Count meant to follow on his own and that the rest of the raiding party did so as to not look cowardly . The Templars " thought that they would be dishonored if they allowed the Count to go before them " . However , another source , Matthew Paris , reported that de Sonnac was forced into the assault by the Count . Robert was " bellowing and swearing disgracefully as is the French custom " , and blaming the Templars and other religious orders for causing the real downfall of the Kingdom . Disgusted , de Sonnac returned to his men and prepared to chase down the numerically superior enemy . Whatever the fact , the three commanders charged into Mansurah with tired men and no reinforcements and were quickly drawn into heavy fighting . Completely surrounded , " like an island in the sea " , de Sonnac refused to surrender and his Templars fought to the last man . Earl Longespee was killed in the fighting , and the Count either fell in combat or drowned fleeing to safety . De Sonnac ' s escape from the city would make him a famous warrior , when many had considered him more suited to diplomacy . With heavy wounds , only one eye and two remaining knights of the original 280 , he fought through the Egyptian army and out of the city , where he found the main Frankish army . He refused to rest and after receiving medical attention he returned and helped repulse a Muslim raiding party . Battle of Fariskur . The Christian forces camped outside the city and were under constant attack . A major assault was launched by the Muslims on 6 April and de Sonnac joined the Frankish charge to meet the enemy . He fought along the riverbank until he was finally overwhelmed by the attackers . Blinded fully by a second injury to the head , he was hacked down and killed by Muslim troops . His death and the capturing of Louis IX marked an end to the seventh crusade . He was succeeded as Grand Master by Renaud de Vichiers . Chronicler . De Sonnac was the first Grand Master to formerly record the intricacies of the Templar hierarchy . He added this to existing archives , codified them and stored them in a safe place so that the order would have accurate records in future years . It is certainly ironic that , for a man responsible for creating the order ' s most in - depth records , there is no indication of when he was born . In fiction . Guillaume de Sonnac is a prominent character in " Crusades " , a graphic novel by Izu , Alex Nikolavitch , and Zhang Xiaoyu , published by Les Humanoïdes Associés , in which he is show as a power hungry plotter .