In 1199, while taking part in a tournament at Ecry-sur-Aisne, he took the cross in the company of Count Thibaud de Champagne and went on the Fourth Crusade. The crusade soon fell under Venetian control, and was diverted to Zara on the Adriatic Sea. Pope Innocent III had specifically warned the Crusaders not to attack fellow Christians; Simon opposed the attack and urged a waiting Zara delegation not to surrender, claiming the Frankish troops would not support the Venetians in this. As a result, the delegation returned to Zara and the city resisted. Since most Frankish lords were in debt to the Venetians, they did support the attack and the city was sacked in 1202. Simon did not participate in this action and was one of its most outspoken critics. He and his associates, including Abbot Guy of Vaux-de-Cernay, left the crusade when the decision was taken to divert once more to Constantinople to place Alexius IV Angelus on the throne. Instead, Simon and his followers travelled to the court of King Emeric of Hungary and thence to Acre.