On August 25, 1270, the King of France, Louis IX, died in the camp of the Crusader army, not far from ancient Carthage. Leaving the port of Aigues-Mortes at the beginning of July, the barons and knights who took the cross after the French king landed in Tunisia a few weeks later. Paralyzed by the constantly delayed arrival of the King of Sicily and exhausted by the heat of the Tunisian summer, the crusaders were quickly weakened by illness, which claimed the life of the king and several high-ranking officials. After several battles with the enemy, the Crusaders evacuated Tunisia in November. The destruction of the fleet off the Sicilian coast by a storm prevented the expedition from continuing its journey to the Holy Land. The survivors had no choice but to return to France. Undertaken at great expense, and preceded by numerous preparations of all kinds, the eighth and final crusade was a complete failure. This book tells the story of the disaster from the acceptance of the cross by Louis IX in 1267 to the return of the Crusaders in the spring of 1271. A disaster to reflect on in these times of tension and confrontation.