only when the Byzantine emperor was in a position to enforce them militarily were they likely to be recognised in practice. The high point of John's diplomacy in the Levant was in 1137 when he extracted formal homage from the rulers of the Principality of Antioch, County of Edessa and the County of Tripoli. The Byzantine desire to be seen as holding a level of suzerainty over all of the Crusader states was taken seriously, as evidenced by the alarm shown in the Kingdom of Jerusalem when John informed King Fulk of his plan for an armed pilgrimage to the Holy City (1142). Religious matters The reign of John II was taken up with almost constant warfare and, unlike his father who delighted in active participation in theological and doctrinal disputes, John appears to have been content to leave ecclesiastical matters to the Ecumenical Patriarch of Constantinople and the church hierarchy. Only when religion impinged directly on imperial policy, as in relations with the papacy and the possible union of the Greek and Latin churches, did John take an active part. He organised a number of disputations between Greek and Latin theologians. John, alongside his wife who shared in his religious and charitable works, is known to have undertaken church building on a considerable scale, including construction of the Monastery of Christ Pantokrator (Zeyrek Mosque) in Constantinople. This monastery, with its three churches, has been described as one of the most important and influential architectural constructions of Middle Byzantine Constantinople. Attached to the monastery was a hospital, of 5 wards, open to people of all social classes. The hospital was staffed by trained layman doctors rather than monks. The central of the three churches was the Komnenian funerary chapel, dedicated to St. Michael. It had twin domes, and is described in the typikon of the monastery as being in the form of a heroon; this emulates the older mausolea of Constantine and Justinian in the Church of the Holy Apostles. Very active persecution of the followers of the Paulician and Bogomil heresies characterised the last few years of the reign of Alexios I. No records from the reign of John mention such persecution, though countermeasures against heresy by the Byzantine Church remained in force. A permanent synod in Constantinople investigated the writings of a deceased monk named Constantine Chrysomallos which had been circulating in certain monasteries. These works were ordered