Intervention of Nur ad-Din, 1163–1164
In 1163, Shawar, the ousted Vizier of Egypt called Nur ad Din for support in reinstating him to his former position as the de facto ruler of Egypt. Nur ad-Din agreed to support his cause - an alliance between Syria and Egypt would ensure the demise of the Crusaders. Little did Nur ad-Din realize that, while his plan would succeed, it would not be he who would enjoy such unity.
On May 1164 Shawar became vizier of Egypt. He was however a mere figurehead to Nur ad-Din who had installed his general Shirkuh as ruler of Egypt. Shawar became unsatisfied with this and called upon the enemy of the Sunni Muslims, Amalric I, King of Jerusalem.
Amalric invades; Second Crusader invasion, 1164
Amalric had his own designs on Egypt. Therefore, when Shawar invited him into Egypt, he could not turn down such an offer. At Bilbeis, Amalric together with Shawar his Shi'ite ally, besieged Shirkuh. However, Nur ad-Din moved his forces against the Crusader state of Antioch and despite being a Byzantine protectorate (Manuel was in the Balkans) defeated and captured Bohemond III of Antioch and Raymond III of Tripoli at the Battle of Harim. Amalric immediately raced north to rescue his vassal. Even so, Shirkuh evacuated Egypt too so it was a victory for Shawar who retained Egypt.