Military history of the Crusader states
The Seljuk–Crusader War began when the First Crusade wrested territory from the Seljuk Turks during the Siege of Nicaea in 1097 and lasted until 1128 when Zengi became atabeg of Aleppo. At the latter date, the chief threat to the Crusaders from the east and north became the Zengids. The conflict was generally fought between European Crusaders and the Seljuk Turks and their vassals. The Muslim Syrian emirates occasionally allied themselves with the Christians against rival states.
Crusade of the Poor
The Crusade of the Poor was the first major popular expression of support for crusading after the fall of the Crusader states in the Holy Land. Acre, the last remaining city of the Kingdom of Jerusalem, fell to the Mamluks in 1291. In August 1308, Pope Clement V issued instructions for the preaching of a crusade to be launched against the Mamluks in the spring of 1309. This was to be a small, preliminary expedition led by the Hospitallers, a religious military order. The preaching of the crusade was to solicit funds and prayers, not direct participation on the part of the laity. In early 1309 the crusade was postponed until the autumn. In June and July 1309, Clement sent letters reminding those bishops charged with the preaching of the crusade north of the Alps that they were to solicit only funds and prayers and to discourage participation. Indulgences were offered to those providing money.