A battle fought on 13 November 1239 at Gaza between a contingent of crusaders and Franks of the kingdom of Jerusalem and the Ayyûbid forces of Egypt, ending in a devastating Christian defeat.
The crusaders under Thibaud IV, count of Champagne (since 1234 also king of Navarre), had decided to fortify the city of Ascalon (mod. Tel Ashqelon, Israel) to protect the southern border of the kingdom of Jerusalem. While they were marching from Acre to Jaffa (2-12 November 1239), Egyptian troops moved up to Gaza. Several prominent crusaders and local nobles, namely Henry of Bar, Amalric of Montfort, Hugh of Burgundy, Walter of Jaffa, Balian of Sidon, John of Arsuf, Odo of Montbéliard, and Richard of Beaumont, ignored the warnings of Thibaud, Peter of Dreux, and the masters of the Templars, Hospitallers, and Teutonic Knights, and decided to lead a group of 400-600 knights against the enemy. Meanwhile the main army was to continue on to Ascalon.
On 13 November the detached force made a rest stop in a valley surrounded by sand dunes that it had failed to secure properly and was surprised by the Muslims. While Hugh of Burgundy and Walter of Jaffa argued in favor of a hasty retreat to Ascalon, Henry of Bar and Amalric of Montfort decided to stay with the infantry and fight. After an initial success of Amalric’s crossbowmen, the Christians were lured into pursuing the Muslims, who feigned a retreat. The Muslims subsequently managed to surround the Christians. In the ensuing close combat, Henry was killed, while Amalric and many others were taken prisoner. Meanwhile Hugh and Walter had reached Ascalon, where they convinced the main army to move to the rescue of the Christians trapped at Gaza. However, help came too late. At the sight of the crusading army, the Muslims merely abandoned their pursuit of the Christians who were fleeing the battlefield.
Following the defeat, the Templars and Hospitallers convinced Thibaud of Champagne to retreat to Acre rather than to pursue the Egyptians and their prisoners. It fell to Richard of Cornwall, in 1241, to have the casualties of the battle buried at Ascalon and to negotiate the release of the prisoners taken by the Muslims. The main sources for this battle are the Eracles, the Gestes desChiprois, and the historical work of al-Maqrizi.