Crusading was a popular cause in the 13th century, and in 1248 Louis joined the ill-fated Seventh Crusade, having first made a fresh truce with England and received assurances from the Pope that he would protect his lands against any attack by Henry. Henry might have joined this crusade himself, but the rivalry between the two kings made this impossible and, after Louis's defeat at the Battle of Al Mansurah in 1250, Henry instead announced that he would be undertaking his own crusade to the Levant. He began to make arrangements for passage with friendly rulers around the Levant, imposing efficiency savings on the royal household and arranging for ships and transport: he appeared almost over-eager to take part. Henry's plans reflected his strong religious beliefs, but they also stood to give him additional international credibility when arguing for the return of his possessions in France.