Nur ad-Din laid siege to the fortified town of Banias at the foot of Mount Hermon. In June, King Baldwin III of Jerusalem assembled a Frankish army and marched to the relief of Banias and its Knights Hospitaller defenders. While Baldwin and his knights camped near Lake Huleh in the upper Jordan River valley, they were surprised and defeated by forces under Nur ad-Din. The chronicler William of Tyre noted that no watch was kept in the Latin camp. Historian R. C. Smail writes that the setback was caused by Baldwin's carelessness and lack of normal precaution when in the neighborhood of the enemy. Baldwin and his surviving soldiers took refuge in the nearby castle at Safad. Losses were considerable. Ibn al-Qalanisi wrote of many Crusader prisoners and severed heads being presented in a victorious celebration in Damascus.