of Burgundy remained to help fortify Ascalon. On 8 October 1240, the English expedition arrived, led by Richard of Cornwall. The force marched to Jaffa, where they completed the negotiations for a truce with Ayyubid leaders begun by Theobald just a few months prior. Richard consented, the new agreement was ratified by Ayyub by 8 February 1241, and prisoners from both sides were released on 13 April. Meanwhile, Richard's forces helped to work on Ascalon's fortifications, which were completed by mid-March 1241. Richard entrusted the new fortress to an imperial representative, and departed for England on 3 May 1241. In July 1239, Baldwin of Courtenay, the young heir to the Latin Empire, travelled to Constantinople with a small army. In the winter of 1239, Baldwin finally returned to Constantinople, where he was crowned emperor around Easter of 1240, after which he launched his crusade. Baldwin then besieged and captured Tzurulum, a Nicaean stronghold seventy-five miles west of Constantinople. Although the Barons' Crusade returned the kingdom to its largest size since 1187, the gains would be dramatically reversed a few years later. On 15 July 1244, the city was reduced to ruins during the siege of Jerusalem and its Christians massacred by the Khwarazmian army. A few months later, the Battle of La Forbie permanently crippled Christian military power in the Holy Land. The sack of the city and the massacre which accompanied it encouraged Louis IX of France to organize the Seventh Crusade. The Seventh Crusade The Seventh Crusade (1248–1254) was the first of the two Crusades led by Louis IX of France. Also known as the Crusade of Louis IX to the Holy Land, its objective was to reclaim the Holy Land by attacking Egypt, the main seat of Muslim power in the Middle East, then under as-Salih Ayyub, son of al-Kamil. The Crusade was conducted in response to setbacks in the Kingdom of Jerusalem, beginning with the loss of the Holy City in 1244, and was preached by Innocent IV in conjunction with a crusade against emperor Frederick II, the Prussian crusades and Mongol incursions. At the end of 1244, Louis was stricken with a severe malarial infection and he vowed that if he recovered he would set out for a Crusade. His life was spared, and as soon as his health permitted him, he took the cross and immediately began preparations. The next year, the pope presided