The first of Longespée's two pilgrimages to the Holy Land was as a participant in the second wave of crusaders of the Barons' Crusade. On 10 June 1240 he left England in the service of Richard, 1st Earl of Cornwall with roughly a dozen English barons and several hundred knights. They made their way to Marseilles in mid-September, and landed at Acre on 8 October. Longespée and Richard's men saw no combat there, but this group did complete the negotiations for a truce with Ayyubid leaders made by Theobald I of Navarre just a few months prior during the first wave of the crusade. They rebuilt Ascalon castle, and notably handed over custody of it to Walter Pennenpié, the imperial agent of Frederick II in Jerusalem (instead of turning it over to the local liege men of the Kingdom of Jerusalem who strongly opposed Frederick's rule). On 13 April 1241 they exchanged Muslim prisoners with Christian captives who had been seized during Henry of Bar's disastrous raid at Gaza five months earlier. They also moved the remains of those killed in that battle and buried them at the cemetery in Ascalon. Longespée almost certainly departed with Richard for England on 3 May 1241.