Outremer
Zengi
The first generation of Crusaders had passed and one era in the history of Outremer was over. The second generation at the beginning seemed to be carrying on the traditions and concerns of the first, but a new factor would soon enter the scene in the form of Zangi of Mosul, who united much of Syria behind him and whose career climaxed with the capture of Edessa in 1144.
Zengi emerged a power at Mosul in the early 1130s. At the beginning of his career, he was preoccupied with events at Baghdad, but by 1133 his position there was secure and he began making moves to the west. The ruler of Mosul and Aleppo always had to be concerned with all four fronts (at least): Baghdad to the east, the Turks and Armenia in the north, Edessa and Antioch to the west, and Damascus and minor emirs in the south. Zengi attacked into Antiochene territory, capturing many of its eastern fortresses. He also marched on Damascus at one point, and on Homs at another point. He caused the Christians great concern, to the extent that Fulk marched north to help out on more than one occasion.
One of these occasions almost proved the King's undoing. In 1137 Zangi was laying siege to Homs, in an attempt to reduce its emir to obedience. Sensing an opportunity to avenge his father's death, Raymond of Tripoli marched out with an army and forced Zangi to raise the siege. Raymond did not dare meet the Muslims in open battle and so retreated before it, sending for help to Jerusalem. Fulk set out with a small army and joined Raymond. Zangi was now besieging the Crusader castle of Montferrand. On the approach of the Frankish army he again raised the siege, but this time the Franks gave battle.
Zangi defeated the Latins soundly. Count Raymond was killed on the battlefield, along with many of the Tripolitans, while King Fulk managed to escape with most of his army into Montferrand. He was immediately besieged. He sent messengers out to Antioch, Jerusalem and Edessa for help.
All areas of the kingdom responded, but not in time. The garrison was running out of supplies, and the walls of the fortress were being battered down by Zengi's siege engines. Fulk asked for terms, not knowing that help was on its way. Zengi asked only for Montferrand itself. Not only would he let the King and all his men go free, he would also free all the captives currently in his possession. Fulk accepted. He left Montferrand at the end of July, meeting the relieving army on the way to Tripoli.
The King was saved, at the cost of a single fortress. Perhaps more importantly, all the Franks now recognized that Zengi was their most dangerous enemy. This helps explain the events of 1139.