Visconti left Liège in 1267 for Paris at the behest of Pope Clement IV who sent him to England to assist Cardinal Ottobono Fieschi, who had been appointed Papal Legate in England in 1265, to support King Henry III in the rebellion of the barons, led by Simon de Montfort. It was during this assignment that Teobaldo became friends with Prince Edward of England (the future Edward I), with whom he went on Crusade. Cardinal Fieschi returned to Viterbo, and participated in the conclave of 1268-1271. Edward took the cross on 24 June 1268, followed Louis IX to Tunisia, and finally reached Acre on 9 May 1271.